Plastic film mulching refers to a measure of covering the ground with agricultural plastic film. Can reduce the impact of raindrops and prevent erosion and crust; It can effectively reduce soil moisture evaporation, conserve moisture during drought and after rain, promote crop absorption and growth, and improve soil water use efficiency; It can keep the soil at an appropriate temperature and humidity, slow down the ground temperature, and last for a long time, which is conducive to the decomposition and decomposition of fertilizers and improve the fertility of the land. Plastic film mulching has the advantages of low cost, convenient use and large yield increase. This is a common measure, which can not only prevent soil erosion, but also increase crop yield. The biggest function of plastic film mulching cultivation is to increase soil temperature. Covering soil with plastic film at low temperature in spring can raise the temperature of 0- 10 cm deep soil layer by 1-6℃, and the highest temperature can reach above 8℃. In high temperature period, if there is no shading, the surface temperature of soil under plastic film can reach 50-60℃, and when the soil is dry, the surface temperature will be higher. However, when crops are shaded or the surface of plastic film is covered with soil or silt, the soil temperature is only 1-5℃ higher than that in the open field, and when the soil is wet, it will be 0.5- 1.0℃ lower than that in the open field, at most 3℃ lower. Due to the influence of cold air at night, the soil temperature under plastic film is only 1-2℃ higher than that in open field. The warming effect of plastic film mulching varies with different mulching periods, mulching methods, weather conditions and plastic film types [1]. Because of the strong air tightness of the film, film mulching can significantly reduce the evaporation of soil moisture, make soil moisture stable and keep moist for a long time, which is beneficial to root growth. In arid areas, soil moisture can be artificially created and supplemented for drought-resistant sowing. Under drought conditions, the soil water content in 0-25cm soil layer is generally higher than that in the open field by more than 50%. With the deepening of soil layer, the water level difference gradually decreases. The crops covered with plastic film grow vigorously and consume a lot of water for transpiration. Under the same management situation, water shortage is easy to occur. Pay attention to irrigation to prevent drought and reduce production. Plastic film mulching can increase the temperature and keep moisture, so it is beneficial to the proliferation of soil microorganisms, accelerate the transformation of humus into inorganic salts, and benefit the absorption of crops. According to the measurement, available nitrogen, potassium and phosphorus increased by 30-50%, 10-20% and 20-30% respectively after plastic film mulching. Plastic film mulching can reduce the leaching, loss and volatilization of nutrients and improve the utilization rate of nutrients. However, the nutrients covered with plastic film are higher in the early stage of crop growth, but tend to decrease in the later stage. When producing vegetables, we should pay attention to late topdressing, otherwise it will affect the yield. In addition, plastic film mulching can avoid soil hardening caused by irrigation or rain erosion, reduce the labor of farming, and make the soil loose and breathable. Can increase the total porosity of soil 1- 10% and reduce the bulk density by 0.02-0.3g? Cm-3 can improve the stability of soil aggregates by 65438 0.5%, and coordinate the conditions of fertilizer, water, gas and heat in soil. At the same time, it can prevent alkali return and reduce the harm of salinization. After plastic film mulching, at noon, the middle and lower leaves of the plant can get 12- 14% more reflected light, which is 3-4 times more than that in the open field. So the apples at the lower part of the trunk can be well colored, with bright flowers and good smoke color. The photosynthetic intensity of tomato can be increased by 13.5-46.8%, and the chlorophyll content can be increased by about 5%, which can delay the senescence period of middle and lower leaves and promote the accumulation of dry matter, thus improving the yield. When the temperature between the plastic film and the surface is high on sunny days, the high temperature of about 50℃ often occurs, which makes the grass buds and weeds die. Using herbicides before and after mulching can prevent weeds from growing and reduce weeding workload. However, poor mulch or not using herbicides can also lead to a shortage of grass. Plastic film mulching can enhance disease resistance and reduce morbidity, because plants grow healthily. Covering with silver-gray reflective film can avoid aphids and reduce the spread of virus diseases. However, plastic film mulching cultivation also has some adverse effects, such as long years of plastic film mulching and incomplete removal of residual film, resulting in soil pollution. Due to the rapid decomposition of organic matter after plastic film mulching, high crop utilization rate, less fertilizer supplement, decreased land fertility, or improper management of plastic film mulching, it can also lead to early maturity, no increase or even decrease in production. Plastic film mulching is not suitable for planting in dry sandy land, barren land and heavy clay land. Because the soil temperature of dry sandy land covered with plastic film is easy to produce high temperature at noon, but it will reduce production when drought is serious. In barren land, it is not convenient to topdressing after mulching, and the base fertilizer is insufficient when sowing, and mulching can not increase production. Heavy clay is not easy to rake flat when it is dry, and it is not easy to stick to the ground after covering. When the wind blows, the plastic film is easily broken and blown away. Therefore, plastic film mulching cultivation must master certain conditions in order to achieve the goal of early maturity, high and stable yield.