Based on fully mechanized working face support working resistance settlement and reliability problem, 15101 fully-mechanized caving face of Jiarui Mine was taken as example, theoretical analysis method，measurement method，load estimation method and empirical formula method were applied to calculate the reasonable working resistance of fully-mechanized caving face hydraulic support,  the reasonable support strength of fully mechanized caving face hydraulic support was got, structural reliability theory was adopted to analyze the safety and reliability of the fully mechanized support, the safe and reliable index of working face support was obtained, the practice showed that the selected support could meet the needs of safe production.