Abstract: It is very important to study overburden failure law for safety mining under water bodies. In order to get overburden failure law, it takes 22111 working face fully-mechanized mining of a certain coal mine for example, uses FLAC^3D numerical simulation software, and it establishes three dimensional numerical model, analyzes and studies overburden failure law induced by the working face mining, then determines the distribution forms and development heights of caving zone and water flowing fractured zone. Compared field measured results with empirical formula calculation results, numerical simulation results show that the use of numerical simulation for predicting the mining overburden failure law has bigger superiority to other methods.