Under certain approximate conditions. The combined external force and combined external torque acting on a wire of length L carrying a current I in a non-uniform magnetic field generated by a long straight current were analyzed and solved using the knowledge of mechanics in college physics. The motion trajectory of the wire′s center of mass C and the change in the wire′s rotation angle were obtained through numerical methods. The motion trajectory of the wire within one rotation period was further studied. The reasons were analyzed from the changes in velocity and acceleration parameters.