A control strategy based on extremum seeking of sliding mode is proposed to optimize conventional clamping force control of continuously variable transmission (CVT). The nonlinear and discrete mathematical model of slip rate is built to prove the special relationship between transmission efficiency of CVT and slip ratio of metal belt,and the extremum seeking of sliding mode controller is designed. The optimal regions of slip ratio are searched with this controller. The optimal slip ratio is got by concussion filtered interference signal. The critical value of system instability is the constraint object which shows the control system has good robustness by strong anti-interference ability of the driver torque. In order to verify the effectiveness and feasibility of clamping force control strategy,simulation platform and real vehicle test platform is established. Simulation and real vehicle verification results show that transmission efficiency is improved by 7.98%-9.98%,fuel efficiency is improved by 1.15%,and fuel consumption is reduced by about 5.54%. By comparisons between extremum seeking of sliding mode control and conventional clamping force control,the control strategy algorithm proposes a new method to meet the needs of improving fuel economy requirement and optimization space.