The finite element analysis software ABAQUS was used to analyze the influence of geometric parameters of the boom on its mechanical properties, providing a theoretical basis for the design of the boom of drag sail device. The results show that: 1) increasing the shell thickness and decreasing the radius of cross section with a constant arc length and increasing the angle of the shell section can effectively improve the automatic expansion capacity of the drag sail device and the support stiffness of the boom. 2) the internal bending stress of the boom is only related to material properties, the radius of cross section r, bending radius R and shell thickness t. As the radius of cross section decreases and the shell thickness increases, the internal bending stress of the boom will increase, which may lead to the plastic deformation of the boom when it is convolved. Therefore, the influence of the geometric parameters of the boom on its expansion capacity and winding performance should be considered comprehensively when designing the boom of the drag sail device.