Abstract: In order to reduce the bit rate of the high speed signal for further processing, a high speed all-optical serial-to-parallel conversion system was designed and demonstrated. The characteristics of the spectral width of the clock pulse and the high speed response of four-wave mixing (FWM) in optical fiber were utilized. A narrow optical division clock pulse stream with repetition frequency of 10GHz was expanded in the time domain by using group velocity dispersion (GVD) effect in optical fiber. Moreover, an all-optical serial-to-parallel conversion function from a 40Gb/s return-to-zero (RZ) format signal to 410Gb/s signals was realized by utilizing four wave mixing process in optical fiber. This scheme is fast in response, transparent in wavelength and bit rate, and capable of increasing channels significantly.