Abstract: Piezoelectric fans make use of the property of the piezoelectric material. The material functions as an actuator to move the plate so as to make the air around it flow. It can be an active cooling technique for electronics. The software Fluent was used with the moving-grid technique to simulate unsteady flow. The frequency of the vibrating plate, length of the piezoelectric fan (flow field's length) and the ratio of vibrating plate's length to the piezoelectric fan's are investigated to study their influence on the wind velocity at the outlet of piezoelectric fans. The results are as follows: increasing the vibrating plate's frequency, the piezoelectric fan's length, or the ratio of vibrating plate's length to piezoelectric fan's in a certain range can improve the wind velocity at the outlet. There is a linear relationship between frequency and wind velocity at the outlet. The wind velocity at the outlet improves more and more slowly with the increase of piezoelectric fan's length. There is a critical value beyond which further increase in the ratio of vibrating plate's length to the piezoelectric fan's decreases the wind velocity at the outlet.