The tip structure is one of the key factors to determine the performance of left ventricular assist device (LVAD) inflow cannulas. The tip structure influences the thrombosis, hemolysis in cannula and left ventricle and suction leading to obstruction in ventricle. We designed four kinds of inflow cannulas that had different tips and built the numerical models of the four historical used inflow cannulas inserted into the apex of left ventricle. We computed the hemodynamic characteristics of inflow cannulas insertion by Fluent software. We researched the backflow, turbulent flow and pressure distribution of the four inflow cannulas. The results showed that the trumpet tipped inflow cannula had smooth flow velocity distribution without backflow or low velocity flow. The trumpet tipped inflow cannula had the best blood compatibility characteristics. The trumpet structure could prevent obstruction. The caged tipped cannula had serious turbulent flow which could possibly cause thrombosis and the low pressure near left ventricle wall and easily lead to ventricle collapse. The trumpet tipped inflow cannula has the best blood compatibility and is difficult to be obstructed. The trumpet tipped inflow cannula is fit to long-term use LVAD.