In order to improve the flow pattern in the foreway of a pump station, the RNG k-ε turbulence model based on the Fluent software was used to simulate the flow pattern in the front inflow forebay of a pump station with a single row of square columns, and the effect of geometric parameters of these square columns on the flow pattern in the foreway was analyzed. The results show that a single row of square columns leads to flow separation, the water flowing through the square columns disperses to the two sides of the foreway, and vortices form behind the square columns. Without rectification measures, the flow pattern is disorderly in the forebay, but it is significantly improved when a single row of square columns are arranged in the forebay. These square columns should be arranged in the forepart and middle of the forebay, not in the backflow zone at the two sides. The flow separation effect decreases and the approach velocity is more non-uniform with the decrease of the width of square columns.