A novel all fiber interleave filter using Mach Zehnder based sampled fiber gratings was proposed and fabricated. The operation principle of this device was introduced, and its performances were analyzed mathematically. In this proposed interleaver, the splitter ratio of coupler, the spectrum of sampled fiber grating and path length difference of two arms are the three key parameters that decide the performances of the interleaver. The interleaver demonstrates channel spacing of 100 GHz.