This paper summarizes the pilot induced oscillation( PIO) flight training and PIO rating( PIOR) method. According to the mechanism of PIO,three factors inducing PIO were analyzed. In variable stability aircraft,key system parameters which could cause PIO were set,high gain flight training tasks were designed. Three pilots completed the tasks,who gave a quantitative evaluation of aircraft PIO tendency using the PIOR. PIO flight training method and assessment method of flight was researched. The results show ...