The open area ratio is an important performance index for microchannel plates(MCPs). The detection efficiency and noise factor of MCPs can be significantly improved by expanding the entrance of the pores, which has potential application in the military and civil fields, such as low-light-level night-vision devices and particle detectors. MCPs with funneled pores prepared through wet etching are difficult to apply on a mass scale because of problems such as poor consistency of the process and difficulty in conforming funnel size caused by selective corrosion. A dry-etching method for MCP flaring was proposed for the first time. The principle and feasibility of dry etching for MCP flaring are described in this paper. A theoretical model was established to investigate the effects of dry etching process parameters, such as etching angle and etching time, on the MCP opening area ratio, etching depth in the channel, etching taper on the channel wall, and other performance parameters. The appropriate range of the process parameters was calculated theoretically, which provides a foundation for experimental research.