The effect of the process parameters on the release rate through the XeF2 etching to release the poly-Si is studied in this paper. The results show that for the cantilever structure the etch rate increases first and then reduces with the increase of the carrier gas N2 flow in the stable chamber pressure, the maximum etch rate is 10.3 μm/min. When the carrier gas N2 flow is the constant, the greater the chamber pressure value, the concentration of taking part in the etch reaction in process chamber is increased, the faster the etch rate. While the chamber pressure is greater than 1 200 Pa, the percentage increase for etch rate decreases with the increasing of the chamber pressure.