The common methods of cam induction hardening are discussed at present. By analyzing the basic motion law of conjugate cam, a new induction hardening mechanism is designed. The motion controlling mathematical model is built on the basis of the kinematic relationship of the transmission of the induction hardening mechanism. Through the mathematical model calculation, we can get angular velocity of the workbench, then realize that single axis on NC machine controls the inductor to make isometric uniform motion relative to the cam surface, so that the cam hardening depth distribution is uniform.