The oil pump models with different gear tooth shapes were established and the internal flow field simulation were taken by utilizing Pumplinx. Then the characteristics of steady state flux and flow pulsation were analyzed. The results were as follows. Compared with the straight gear pump, the flow pulsation of other toothed gear pumps was much lower, although they flowed more slowly at the low and medium speeds. Especially the flow pulsation of dislocation gear pump was much lower than straight gear pump. Moreover, It decreased 27% at 1 100 r/min and 35% at 2 700 r/min comparing with the straight gear pump. Finally the straight gear pump flow was practically tested and the experimental results match the simulation very well. Therefore, it was proved that the internal flow field models were correct, and then this might technically support the oil pump development.