1. The testamentary witness shall be an adult with full civil capacity. According to the provisions of the General Principles of the Civil Law, citizens who have reached the age of 8 are adults with full capacity for civil conduct, can conduct civil activities independently, and are persons with full capacity for civil conduct. Citizens who have reached the age of 16 but not the age of 8, and whose main source of income is their own labor income, are legally regarded as persons with full capacity for civil conduct, and may serve as witnesses of their loss. However, persons with limited capacity and persons without capacity cannot act as testamentary witnesses.
 2. A testamentary witness shall be a person who can understand the contents of the will and all the words of the will. Although some people have full capacity for civil conduct, they do not have the capacity to witness wills.
 3. He has no interest in his successor or testator. Because people with interests are more likely to be driven by their interests and make false proof.