Abstract: In order to study the properties of the ion barrier film of microchannel plate(MCP), the Al2O3 ion barrier film was successfully fabricated on the input-face of MCP by the e-beam evaporating method．The optimal thickness of the ion barrier film was 2 nm. After measurement，the electron transmittance characteristics through the ion barrier film for unfilmed and filmed MCPs were shown. The relationship between the thickness of the ion barrier film and the dead voltage was given, the dead voltage of Al2O3 ion barrier film with the thickness of 2 nm and 4 nm was 150 V and 200 V, respectively. The stopping function on incident ions was analyzed by Monte-Carlo method, the barrier rate for 2 nm and 4 nm Al2O3 ion film was above 40% and 86% , respectively .Besides, the electrical characteristics of unfilmed MCP were tested, and the results showed that with the Al2O3 ion barrier film of 2 nm and 4 nm, the electron gain of MCP reduced by 51% and 81%,respectively.