Legal analysis: the will written by the heir is invalid. Entrusted will is also a form of will, which should meet the following conditions: 1. The testator is a person with full capacity for civil conduct, and a person with limited capacity for civil conduct and a person without capacity for civil conduct cannot make a will; 2. The testator's thought expresses the truth; 3. The property disposed of by the will is the legal property of the testator, which should be witnessed by more than two witnesses, and has no interest with the heir. One of the witnesses wrote the book and marked the year, month and day.

Legal basis: Article 143 of the Civil Law of People's Republic of China (PRC) A civil juristic act is valid if the following conditions are met:

(1) The actor has corresponding capacity for civil conduct;

(2) the meaning is true;

(three) does not violate the mandatory provisions of laws and administrative regulations, and does not violate public order and good customs.