A fluttering-based miniaturized wind energy harvester is presented. The harvester is comprised of a lead zirconate titanate(PZT) piezoelectric beam and a flexible beam. The flexible beam vibrates the PZT beam when flutter motion triggers. The flexible beam flutter motion is investigated in a small wind tunnel. It’s found that flutter occurs between of cut-in and cut-out critical wind speeds. Effects of the flexible beam length and width on the device characteristics are investigated. It’s found that with the increase of the length, the critical wind speed, fluttering frequency, output voltage and power of the device decrease. While with the increase of the width, the critical fluttering speed is nearly unchanged, and the fluttering frequency, output voltage and power of the device all increase. The minimum critical wind speed of the harvester is 6.4 m/s and the maximum power is 1.30 mW. The results show that the flexible beam structure can reduce the critical wind speed and increase the output power of the PZT beam. The feasibility of the wind-induced vibration energy harvester is confirmed.