Objective To design a percutaneous left heart assist device (blood pump) which can be used in critical cardiovascular diseases. Methods According to the aerofoil theory, a percutaneous left ventricular assist device was designed. The flow produced by blood pumps with 3 different design parameters (rotation angle of the blade, distance of the outlet from the blade, length of the outlet ) was measured so as to choose the optimal design of the blood pump. Results The flow was measured with a simple flow measurement device. When the blood pump was designed to adopt a single blade with the rotation angle of 720°, or the distance between the outlet and the blade was 0 mm, or the length of the outlet was 4 mm, the flow of the blood pump was the maximum. Conclusions To choose the design parameters that produce the maximum flow can contribute to manufacture a percutaneous left ventricular assist device with the function of pumping in vitro, which will provide a theoretical and data support for the eventual development of the percutaneous left ventricular assist device in clinic.