Research conclusions: In order to make the prediction of water bursting volume more closed to the real situation，more reasonable and more scientific，on consideration of the strength reduction factor of the fissure and the asymmetry of the boundary condition，the calculation should be made for the steady flow with the parcel superposition method，the calculation should be made for the non － steady flow with the osmotic coefficient that conforms to the real situation and thickness of the water － bearing stratum，the water bursting volume should be predicted by using the effective catchment area when the underground runoff method is used on the base of the analysis the topographic and structural conditions， and the hydrology method has macro estimate role，so it is unsuitable to be used for the quantitative evaluation． When the condition is allowable，the numerical model should be established for calculation，especially to establish the 3D flow numerical model．