Abstract: Based on the Mohr-Coulomb yield criterion and the Formula of water inrush coefficient, we obtain a new method to evaluate and predict water-inrush from coal seam floor. And use it to predict water-inrush of some important point of the Xianfeng mine in Yunnan Province. Then compared with the result of the Formula of water inrush coefficient, find that some areas non-water inrush with the result of the Formula of water inrush coefficient, but it is possible to water inrush with the new method of this paper. On the other hand, we analysis failure characteristics of floor water inrush with FLAC3D software. The results of numerical simulation are compared with the results of the new evaluation method. The two results are basically consistent, further verified the rationality of the evaluation.