Abstract： Objective To study the flow field of Luo-Ye (L-Y) pump, a ventricular assist pump,and to compare it with Berlin Heart (B-H) pump. Methods In this study, computational fluid dynamics (CFD) was adopted to study the flow fields of L-Y pump (80 ml)and B-H pump(80 ml). Between two types of pump, a comparison was made of their typical cross sections in their streamline and pressure distribution charts. Results By streamline charts, continuous streamline flow was demonstrated during early diastole,and steadily involved in a coherent spiral vortex during mid-diastole in L-Y pump. In B-H pump, similar streamline flow was observed during early diastole while the vortex was not formed during mid-diastole. At systole, blood efflux was found in both pumps, with even distribution of streamlines in L-Y pump due to its cross design and somewhat less even streamline distribution in B-H pump owing to the parallel structure of its outlet and inlet. The pressure distribution charts showed a number of local low-pressure areas during diastole in B-H pump but only one in L-Y pump. Similar pressure distribution during systole was found in both L-Y and B-H pumps. Maximum speed of L-Y pump and B-H pump was 0.472 m/s and 0.486 m/s during early diastole; 1.33 m/s and 1.34 m/s during middle systole. Conclusions L-Y pump may favorably preserve a linear flow field as well as rational distribution of streamlines and pressure, in contrast to frequent occurrence of small turbulence at outlet and inlet, as well as less even distribution of pressure seen with B-H pump.