Abstract: In view of different patterns of intake, pumping station arrangement is usually divided into two types of the forward and lateral intakes. When the water passes over the side-inlet forebay of the pumping station, there is an angle between the main flow direction in the side-inlet forebay and its inflowing direction. At this time some undesirable flow patterns such as the main flow direction moving off the wall, reverse current and vortex are caused by the motion characteristics of the flow along the curved section, thus it is difficult to form a good inlet condition for the pump and affect the safe operation of the pumping units. A 3-D mathematical model to simulate the water flow in both the side-inlet forebay and the inflowing channel of the first phase of Cuddalore pumping station is developed in this paper. The RNG κ-ε turblent model is used to close the Navier-Stockes equations and the SIMPLEC algorithm method is adopted to calculate the flow field, which are finished by the Fluent 6.3.26 software. Here, two schemes(the original and the rectifying schemes) on the Cuddalore pumping station are calculated. The distribution characteristics of the hydraulic parameters including velocity, vorticity and water surface line about the two schemes have been compared, the uniformity of flow distribution in the side-inlet forebay based on the target function of the velocity distribution along the typical cross-sections is also analyzed. Finally it is more exactly understand the characteristics of water flow in the side-inlet forebay, and the analysis results show that the reasonable rectifying measures can effectively improve the flow pattern in the forebay.