Room-and-pillar method is used for mining in most gypsum mines,and a top gypsum layer with a certain thickness in stope is reserved to keep the roof stabilization of stope.The top-safeguarding layer is one of important factors to influence roof stability of mined-out area.Based on analysis of failure patterns of top-safeguarding layer of stope in gypsum mines and the data results from the on-site survey in some gypsum mine in Changde,Hunan Province,the factors influencing the stability of top-safeguarding layer was analyzed by theoretical calculation,a reasonable thickness of top-safeguarding layer was presented out according to the mining structure parameters for the gypsum mine.It provides the theoretical basis for the thickness design of top-safeguarding layer of stope in gypsum mines.