Objective To study the hemodynamic effect of the convertible vena cava filters on treating pulmonary embolism with different thrombus diameters and contents. Methods Three kinds of simulated filter models with the same diameter but different filtering structures (L-style, S-style and W-style) were built and then the hemodynamics of the filter after its implantation into the vessels was analyzed by using computational fluid dynamic (CFD) method. Results Without thrombus in the vessels, three kinds of filters in blood had some obstructive effects and increased the average outlet velocity. While the L-style filter caused the maximum average outlet velocity, the S-style filter was in the middle, and the W-style filter was the lowest. Under the condition of thrombus, the structures of the filter rods had no obvious effect on the average outlet velocity of blood flow and thrombus, and differential pressure of blood flow and thrombus between inlet and outlet. With the increase of thrombus’s diameter and content, the hemodynamic factors showed varying degrees of decreasing tendency. The wall shear stresses (WSS) on three kinds of filter rods caused by blood flow were in normal ranges, and WSS on the lower end of filter supports, the joints of supports and filter rods were below the minimum value, where thrombosis was easy to occur. Conclusions The hemodynamic effect of three kinds of convertible vena cava filters with different filtering structures, different thrombus diameters and contents in vessels were analyzed by using CFD method, which would provide theoretical references for the design and development of novel filters.