Microchannel plates (MCPs) are two-dimensional arrays of microscopic channel electron multipliers as the key component of the image intensifier. In this paper, the plasma etching process of large-size microchannel plates based on silicon is developed. Firstly, the etching of micro groove structure is researched for measure easily. The influences of the process parameters on the etching rate and sidewall verticality, such as oxygen flow, the pressure and the inductively coupled plasma (ICP) power, are studied. The results show the etching rate becomes larger and larger with the increasing of the pressure and ICP power. And the oxygen flow contributes to etching. But the sidewall verticality is worse with increasing oxygen flow. Though parameter experiment, the optimized parameter is got: the pressure 10mTorr, the ICP power 600W, the oxygen flow 6sccm. Using this parameter to etch micro-channel array, the microchannel array of largescale is got with pore 10μm, pitch 5μm, aspect ratio 20:1.