Based on wet etching theory, the silicon microchannel structure after electrochemical etching was released in TMAH solution to obtain the through-hole microchannel. The silicon wafer with the different resistivity was selected as the substrate of microchannel plate, the TMAH solution was selected in mass concentration of 28.5wt%, and the SiO<sub>2</sub> passivation layer with the thickness of 200nm was prepared by thermal oxidation for protection of side-wall of microchannel. Contrary to the problem encountered in wet etching, Firstly, the corrosion characteristics of silicon and SiO<sub>2</sub> thin film in TMAH solution were investigated, respectively. In addition, the effects of the pH values of TMAH solution on corrosion characteristics in microstructure releasing of silicon microchannel were studied and analyzed. The experiments show that the silicon wafer with high resistivity can be easily etched, the etching rate of SiO<sub>2</sub> film in TMAH is uniform, and adjusting the pH value of etching solution to make it constant during etching can effectively increase the corrosion rate and decrease the surface roughness of samples.