The purpose of this study is to improve the transmitting efficiency of CVT by reducing pulley thrusts and preventing a rapid increase of belt slipping speed. The transition of belt slip from micro slip to macro slip was simulated by a spring-mass model. It was revealed that the power transmitting behavior could be expressed by the magnification factor. We proposed a new control strategy of pulley thrust using the magnification factor. The torque ratio was stabilized on around 1.0 and the transmitting efficiency was improved at any condition of input torque.