Aiming at the shortcoming of the integral accumulation in the process of CVT ratio adjusting control, which is caused by the general PID control method, a new ratio adjusting control system based on the shift integral PID control method was designed. The theory of CVT ratio adjusting process and the enhanced control method were analized. The enhanced PID parameter tuning principle was presented. The test-bed of CVT ratio adjusting control was devised and adopted to do the CVT ratio tracing experiments. The experiments of step ratio from 0.45 to 1.45 and from 1.7 to 0.7 were made. The experimental results proved that the new ratio adjusting control system and the enhanced PID parameter tuning principle were valid, which made the real ratio trace the object ratio rapidly and steadily. The control performance of CVT ratio adjusting was improved.