The influences of structure parameters of microchannel plate， such as opening area ratio， thickness， electrode depth， ion barrier film and input enhancement film on noise factor， were studied by comparative measurement method. The results show that the noise factor decreases with the raising of opening area ratio； increases with the raising of thickness； increases with the raising of input electrode depth； increases by ion barrier membrane； decreases by the input enhancement film. The influence of ion barrier film on noise factor is the most， and the influence of thickness on noise factor is the least. The structure parameters of microchannel plate not only affect the noise factor， but also affect other parameters such as gain and uniformity. In order to reduce the noise factor of microchannel plate， the most feasible method is to increase the opening area ratio to 68 %， and then make a layer of MgO₂ on the input end of microchannel plate. This will reduce the noise factor of microchannel plate close to 1 behaved in the ideal microchannel plate.