In order to solve the problems of low manual welding efficiency，poor weld quality，poor weld mechanical properties and air tightness，a four-coordinate axis control moment gyro shape-follow welding device was developed to adapt the butt welding of circular and non-circular shell and frame.The mechanical structure of the shape-follow welding device was designed，the brazing actuator was built，the control system of the shape-follow welding device was developed，and the welding test and performance test were carried out.The results show that the developed shape-follow welding device can fully meet the requirements of sealing welding between the shell and frame of the control moment gyro,the working efficiency is greatly improved，the weld surface is uniform and beautiful，the temperature rise in the welding process is small，the internal parts of the shell will not be damaged，and the mechanical properties of the weld and air tightness are both significantly improved compared with manual welding.