During the transition process from "family elderly sustainment"to "social elderly sustainment", and the trend of diversification of "family elderly sustainment " and socialization of its development mode, we should pay attention to law of descent when study on the legal protection system of family elderly sustainment. We need to improve the system of the elderly support, adjust the rank of dependents, enlarge the endowment scope, extend the endowment obligation with spiritual support, and reform the execution and collection model of alimony. We also need to construct the guardianship system for the elderly, including the selection for the guardians and defining their obligations.