Objective To explore the accuracy of the multiplication coefficient method and the moment synthesis method for determining the spatial position of the center of gravity (CoG) of the human body based on machine vision. Methods The mechanical measurement platform was built, and the three-dimensional (3D) human body CoG measurement methods under static and dynamic conditions were designed to calculate the space coordinates of the CoG. Through experiments, the calculation accuracy of the multiplication coefficient and moment synthesis method were studied and analyzed. Results In the static experiments, the calculation results of the torque synthesis method were more accurate than those of the multiplication coefficient method for each dimension. The errors in the 3D CoG of the human body in the X, Y, and Z directions calculated using the torque synthesis method were 3.9%, 4.1%, and 8.5%, respectively. In the dynamic experiment, the average and relative errors of the torque synthesis method in the X or Y direction were lower than those of the multiplication-coefficient method. When the action decomposition method was used to analyze the height direction of the CoG along the Z axis, the final rendering effect of the torque synthesis method improved. Conclusions The accuracy of the 3D CoG calculated by the moment synthesis method was relatively high, and was closer to the measurement data of the mechanical measurement platform. The 3D CoG calculated using the moment synthesis method can replace the mechanical measurement platform and can be used in subsequent studies.