Abstract: Resolution and MTF are two important parameters of an image intensifier. The characteristics of the two parameters of a double-proximity focusing image intensifier were analyzed by means of several expressions based on the Fourier spectral theory of linear systems. Two theoretical limiting resolutions were obtained by calculation under a series of theoretical and technologic conditions, for both constructive modes of double-proximity focusing image tubes, in which one is a normal mode of photocathode/MCP/phosphor screen, and another is a mode of electron-internal amplification photocathode/phosphor screen. The calculated results are 96.6lp/mm and 98.1lp/mm.