The Interleaver used in the multiplexer or demultiplexer is a key device of the future DWDM for the limited bandwidth resources in fiber-optic communication. Based on the coupling-mode theory, the transmission properties of nonuniformly sampled FBGs are numerically simulated with the transfer matrix method. The basic principle of optical Interleaver based on non-uniform sampled fiber gratings（SFBG）is introduced. The design example, whose channel interval is 0.8nm and the peak reflectivity is 80%～95%, is presented. The channel intervals are steady and uniform. The delay spectra of each channel are congruous, and the delay dither is less than 100ps.