The invention belongs to the field of large-scale heavy-duty robots, in particular to a projection kinematics control method of large-scale heavy-duty mechanical arms. It includes the following steps: establish a three-dimensional geometric model of the mechanical arm according to the actual mechanical arm; set multiple projection surfaces; perform projection mapping on the three-dimensional geometric model, and obtain the joints J1-J4 and the end point EE of the end effector on each projection surface The projection; according to the three-dimensional geometric model and the projection on each projection surface, the joint angle θ is obtained 1 , θ 2 , θ 3 , the elongation of J4 and the corresponding relationship with EE. Get the joint angle θ according to EE 1 , θ 2 , θ 3 The rotation angle is used as the input value of the joint motor, and the actual angle of the joint is used as the feedback value, and the joint rotation is controlled through closed-loop control to realize the movement of the mechanical arm. The projection kinematics control method proposed by the present invention is an analytical solution method, and compared with other numerical solution methods, iterative solution is not required, the solution efficiency is high, and the real-time requirement of the control system is guaranteed.