The numerical simulation of flow field of a new rectangular suction inlet installing guide plates with different rake angles was carried out by means of the K-ε turbulence model based on the Fluent hydromechanics calculation software. And that the influences of different rake angles of the internal guide plates on the flow field were analyzed. Consequently, the optimal rake angle of 45° was defined at last. Finally, the practical rectangle suction inlet, according to the numerical simulation results, was developed by installing internal guide plates with the optimal rake angle, which optimizes the distribution of internal and external flow field and improves the average side velocities of flow. Practical test results indicate that the new rectangular suction inlet could realize the uniform thickness collection to achieve the smooth work surface when collecting the bulk materials.