A criterion to determine the maximum resolving power of a resolving power test chart by using Fourier power spectrum is proposed. It is an objective evaluation method, in which the Fourier frequency spectra of the resolving power test chart are analyzed and processed according to the optical information processing principle. The mathematical model of Fourier power spectrum is derived. The relations between the resolving power of the test chart and the critical maximum are defined through theoretical calculation and analysis of Fourier power spectrum of the test chart.