Abstract: In order to meet the different ventilation requirement for different driving distance, the impeller structure of fan was designed and the blade angle was adjustable. The structure of impeller was compact, the cost of manufacture was low, and the synchronous adjustment could achieve for different working conditions. On the premise of meeting the ventilation and wind pressure under different working conditions, the fan could operate economically and efficiently. The modal analysis was carried out for the integral structure of impeller by LMS modal test software, the modal parameters of the impeller were obtained through the test, which provided the basis for avoiding the impeller resonance. Meanwhile, the vibration signals were tested from different working conditions and different locations, main causes of vibration in different positions were obtained by analyzing the collected vibration signals, which provided the reference for the optimization of fan structure.