Abstract: Based on analysis of surface movement observation data from Sima Colliery,surface movement characteristic of full-mining caving mining under thick loose bed was researched.The influence of loose bed,lithology and thickness of bed rock on surface subsidence was revealed by numerical simulation.The cause that surface subsidence ratio was larger under thick loose bed was explained.The result might provide important reference for full-mechanized caving mining under thick loose bed when mining under railway,village and buildings.