The invention belongs to the field of pump station application and relates to a design method for an oblique inlet passage used for a pump station. The method comprises the steps of giving a few parameters including design condition flow Q, design condition lift H, a design condition speed n, an impeller diameter D0 of a pump for the pump station, and an inlet tilt angle theta, to calculate main geometric parameters of the oblique inlet passage used for the pump station, wherein the main geometric parameters include an outlet cone angle gamma of the flow passage, a height Hw, relative to the bottom of the flow passage, of the center of a water pump impeller, an inlet width Bj of the flow passage, a length XL of the flow passage, a bottom tilt angle beta of the flow passage, an inlet height Hj of an inlet section, a length HZ of a cone section, a top tilt angle alpha of the flow passage, and a waterflooding depth H1 of a pipe opening. By adopting the bell inlet passage used for the pump station, inlet flow conditions are improved to a certain extent, and hydraulic loss of the inlet passage is greatly reduced, so that the stability and efficiency of operation of the pump station are improved; the method is high in practicality and convenient to apply; the design quality of the oblique inlet passage is ensured; and safe, stable and efficient operation of the pump station is ensured.