Abstract: The organic membrane is used as a temporary substrate for preparing the Al₂O₃ ion barrier film, and its compactness and thickness significantly affect the compactness, the electrical transmittance characteristics of Al₂O₃ ion barrier film and the electrical characteristics of ion barrier microchannel plate (MCP). The non-solvent component was changed from ultrapure water to NaCl solution, and the compactness and thickness of the organic membrane prepared by different NaCl solution concentrations were analyzed by metallographic microscope and step test analyzer. The compactness, the electrical transmittance characteristics and the electrical characteristics of ion barrier MCP prepared by the corresponding organic membrane were measured. The research results show that when the concentration of NaCl solution is 0.05 g·ml⁻¹, the organic membrane has high compactness, and the Al₂O₃ ion barrier film is compact and has small gain loss of MCP, which is the optimal non-solvent component concentration.