This research designs a wireless measurement system using flexible piezoelectric composite film sensor. The system mainly includes piezoelectric film sensor, interface circuit module, AD acquisition module, data processing module and wireless transmission module. The piezoelectric film sensor converts structural vibration information into Piezoelectric signal, the system amplifies, collects, wirelessly transmits and receives the piezoelectric signals. A new method to invert the structural strain by collecting voltage is proposed, The transfer function of piezoelectric signal is derived, and the relationship between acquisition voltage and strain is established, therefore, dynamic strain measurement can be achieved since the frequency and the strain amplitude of the structural vibration can be calculated inversely based on the collected piezoelectric signal. Experimental results indicate that the system can accurately measure the vibration frequency and strain of the structure, and the distance for wireless strain measurement by this system can reach 40 meters, the proposed wireless strain measurement system can partially replace the conventional wired strain measurement system so that it has great potential in engineering applications.