A composite solar cell back membrane comprises a weather-proof layer, adhesive layers, basic materials and a bonding layer. The adhesive layers are formed by coating compositions on the surfaces of the basic materials through solidification, wherein the compositions comprise the following components, by weight, 100-200 parts of adhesives, 8-18 parts of curing agents, 8-35 parts of polyhedral oligomeric silsesquioxane and 200-390 parts of solvents, the polyhedral oligomeric silsesquioxane (POSS) is the POSS containing hydroxyl or the POSS containing isocyanate groups, and the thickness of the adhesive layers ranges from 5 microns to 15 microns. The composite solar cell back membrane has good humidity and heat resistance and flame resistance no edge shrinking phenomenon exists, and the service life of solar cell modules is guaranteed.