Abstract: In the experiment, the vibration of a micro cantilever varying with the jet velocity is studied. It is suggested to measure the micro scale jet velocity based on this mechanism. A copper thread with length 56.2mm, diameter 0.07mm is used as the micro cantilever. The jet velocity comes from a micro nozzle with diameter 0.36mm. The vibration of cantilever is investigated with a high-speed camera while the jet velocity varying between 2.7~27.3m/s.The result shows that the vibration amplitude increase with the jet velocity while the nozzle is amied at 3/5 of the canti-lever length.But while the nozzle is aimed at 9/10 or 3/5 of the cantilever length, the amplitude stops increasing at high jet veloicty. A hall sensor and a magnet are used to measure the vibra-tion. The output voltage increases linearly with the jet velocity, while the nozzle is aimed at the 3/4 of the cantilver lenth. But at the other positions, the viburation is not inneratic because the attached magnet change the mass distribuion of the cantilever.