Historically, it was Liu Yan who did these three major things. During his tenure, Liu Yan accomplished three major things: 1. Reform of water transportation. First, manpower was organized to dredge the river, and 2,000 strong water boats were built, and sergeants were trained to transport grain. Every ten boats formed a team, and the officers were responsible for escorting the transportation. He no longer conscripted strong men along the river to serve, but used the government's salt profits to hire boatmen. Pei Yaoqing's method was followed and developed, dividing the water transport route into four transport sections, and setting up warehouses at the junctions of rivers to store grain for transshipment. Since then, the efficiency of water transportation has been greatly improved, and salt and grain from the south have been continuously transported to Chang'an. 2. Reform the salt policy. He pioneered the salt policy of private collection, official sales, and commercial sales, which reduced cumbersome intermediate links, met the needs of the people, reduced the burden on the government, and increased the salt profits collected by the government. Originally, it was only 600,000 yuan per year. By the end of the Great Li period, it had increased to more than 6 million yuan, accounting for half of the national fiscal revenue, which was used to pay for water transportation and various government expenses. 3. Reform the fiscal system. He established an economic information network and selected diligent, honest and capable scholars as officials to report private production conditions to superiors on a regular basis; he also pioneered the "Chang Ping Law" and "If it is rich, it is expensive to take it, and when it is hungry, it is cheap" to stabilize prices. , stabilize the society; his financial policy of "putting the people first" had a profound impact on later generations. He always appointed people on their merits, acted resolutely, and was honest and honest. His series of financial management policies, measures, and methods were adapted to the dilapidated economy of the Tang Dynasty and the current situation. In order to meet the needs of society, the economy of the Tang Dynasty was restored and developed, and the people were able to recuperate, making an immortal contribution to the resurgence of the Tang Dynasty. Looking at Liu Yan's life, he had a smooth official career, but he was able to understand the hardships of the people's livelihood, and his strategies were outstanding throughout the ages. He is the dragon among men.