The Xixia Institute Anti-regulation Reservoir is a coordinated project of Yellow River Xiaolangdi Water Resources Project. According to the project geological situation of powerhouse dam section of the reservoir, this section project foundation treatment uses horizontal middle-brackets-like “［” shape concrete cut-off wall as anti seepage. For understanding the motion law of underground water and the control effect of seepage-proof measures, three dimensional seepage calculation analysis for the power plant workshop dam section is conducted. The analytic result shows as follows：The selection and arrangement of seepage control measures in the powerhouse dam section are reasonable overall. The bottom plate at the apron section withstands a rather great pressure, seen from the contour-line distribution diagram of uplifts. Therefore, it is suggested that the thickness of concrete bottom plate of the apron should be taken a gradual thickness from 1.0-0.6 meter to ensure the powerhouse dam section safe operation.