Abstract: The speed ratio control of CVT is the key technology to optimal fuel efficiency of the power system． Ai- ming at the problem of slow response and difficulty of real-time precise control for traditional PID ratio control， CVT target speed ratio decision method based on Markov model for predicting power demand was proposed． K- means algorithm of cluster analysis was used to solve the problem． The boundary value of the different moments of the moment demand value was used to divide the state space of the dynamic demand Markov model，and the de- mand torque law obtained by the NEDC cycle condition was calculated． The speed ratio control method of the pre- control plus integral separation PID was proposed． Introducing the differential first and adding the speed ratio pre- control system to determine the target speed ratio change rate can achieve fast follow-up of the speed ratio，and at the same time weaken the speed ratio overshoot phenomenon． The main and driven wheel pressure control strategy was proposed，and the PID controller with Smith correction was adopted． This method can prevent the system from overshooting and make up for the defects of the hydraulic system． The bench test shows that this method can sup- press the overshoot phenomenon in speed ratio control and improve the speed ratio control accuracy．

Key words: continuous variable transmission, power demand, ratio decision, control