Due to the advantages of compact structure, stable operation, and low cost, the gerotor pumps are widely used in the cooling and lubricating system of automobiles. The multi-arc combined gerotor pump is a gerotor pump with a special profile. In this paper, the calculation method of the inner and outer rotor profile of the above-mentioned pump is introduced, and its meshing characteristics are analyzed. In general, three kinds of clearances would be processed to ensure the operation of the pump, named as tip clearance, axial clearance, and radial clearance. These clearances have a great impact on the performance of the pump so that it is important to design them. In response to this problem, this paper established a flow field characteristics model of the multi-arc combined gerotor pump based on computational fluid dynamics (CFD) method, and the effectiveness of the model is then verified through experiments. The influence of the three types of clearances on the flow field characteristics of the pump is analyzed. The results show that reducing the values of the three types of clearance will increase the average outlet flow of the pump, but will inevitably increase the flow rate irregularity at the same time in most cases, among which the impact of the tip clearance is the most significant. Besides, as the clearance value reduces, the amount of flow rate increase will gradually decrease. The conclusions of this paper provide data support for the selection of the clearance value of the pump under different working conditions.