In order to improve the cavitation characteristics of cycloidal gerotor pump, a convex tongue oil groove structure was put forward with an increasing limit of oil flow, and the structure model of cycloidal gerotor pump convex tongue was established. The RNG k-ε turbulence model was used to simulate the internal cavitation flow of cycloidal gerotor pump under different working conditions, the cavitation characteristics of cycloidal gerotor pump convex tongue oil groove were analyzed at different speeds and rotor positions, and the gas rate and axial gas bearing rate of different monitoring points were further studied. And the cavitation characteristics of the cycloidal gerotor pump at different rotation speeds and different inlet pressure conditions were tested and compared. The results showed that the structure of the convex tongue can reduce the cavitation at three kinds of rotational speed, the improved cavitation position was mainly located near the maximum intertooth volume; the convexity groove had the most obvious improvement in the air rate of the rotor region at high speed, less effective at low speed; the cavitation along the axial direction had an inhomogeneity, the bottom cavitation was more serious in the minimum intertooth volume of the inlet side, and the cavitation in the upper part of the rotor was more serious in the larger tooth space. The volumetric efficiency simulation value of the cycloidal rotor pump was in good agreement with the experimental value. The volumetric efficiency of the tongue oil groove was higher than that of the original model under different inlet pressures, and the cavitation characteristics of the tongue oil groove were better than that of the original model.