A criterion to determine the limiting resolving power of film by using Fourier power spectrum is proposed in this paper. It is an objective evaluation method, in which the Fourier frequency spectra of the resolving power of film are analyzed and processed according to the optical information processing principle. The scale to objectively testing the resolving power of film is derived through analysis of the Fourier power spectrum critical maximum coordinates of the film. The similar linear relations between the resolving power of the film and the critical maximum are defined.