Driven by electro mechanical converter of electromagnet, the traditional pneumatic PWM proportional valve has the disadvantages of slow response and poor control precision etc. To solve this problem, a novel piezoelectric direct drive type pneumatic PWM proportional valve driven by piezoelectric converter which has the advantage of fast response is presented. On this basis, its physical prototype is developed and its dynamic characteristic experimental is researched. The effect of PWM carrier frequency, carrier amplitude and proportional control coefficient (P) on the valve performance is analyzed. It is shown from comparison experiments with the traditional same level electro pneumatic PWM proportional that the valve has fast response and high steady precision, with good prospects for industrial applications.