Abstract: In order to encrypt color image, a method based on Fourier transform and asymmetric cryptosystem is proposed. Firstly, a color image is separated into three primary components: red, green, and blue. Then Fourier spectra of the three gray images are intercepted respectively and combined into a target image, and the target image contains most of the original color image information. The amplitude and phase of this target image are encrypted using asymmetric cryptosystem, which means the original color image is encrypted. In this paper, the theoretical analysis and computer simulation are proposed, and the experiment results verify the feasibility of this method.