The invention discloses a metal hydride in situ polymerization and cladding passivation method, and is characterized by comprising the following steps: (1) dissolving 3,3-diazido methyloxetane and tetrahydrofuran (BAMO-THF) copolyether and a curing agent into anhydrous ethyl acetate, and preparing into a dilute solution; (2) putting metal hydride into the dilute solution and performing ultrasonic dispersion to form suspension liquid; (3) stirring and warming to the temperature of 40 to 60 DEG C, stirring for reaction, and recycling the solvent ethyl acetate by evaporation after the reaction is ended; (4) a product obtained after the solvent is removed completely by evaporation is dried and cured in a drying oven, so as to obtain the clad passivated metal hydride. According to the metal hydride in situ polymerization and cladding passivation method provided by the invention, the BAMO-THF copolyether is used for in situ polymerization and cladding of the metal hydride, and the treated and obtained metal hydride is insensitive to water in air. The own energy performance of the metal hydride is not affected while passivating the metal hydride.