Fractured rock masses with many fractures will make the hydro-mechanical characteristics more complex. However, traditional equivalent continuous method just generally reflects the mechanical characteristics for the rocks including large fractures. In order to simulate the mechanical characteristics of the fractured rock masses under complex geotechnical environment, a new method based on Discontinuous Deformation Analysis (DDA) was forward to research on the hydro-mechanical effect. And use the method to analyze the dam foundation, the results compared with that considering non-coupling effect indicated that this model could reflect the hydro-mechanical effect in detail. In addition, FEM and DEM were applied to research on the distribution of the water head, displacement and stress under the same conditions, the results agreed with that by DDA, which further verified the feasibility of the forward method. In addition, the results about the water head and stress analyzed by DDA was greater than that by FEM and DEM, the reason was that this model simultaneously considered the normal deformation and shear deformation of the fractures. Therefore, the forward coupling method based on DDA will provide a research technique for seepage control and stability assessment of the rock engineering.