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With the development of the space industry in China, the demands for transmit rate from satellites to receivers on the ground is getting higher and higher. In order to meet the demands of high-speed transmit rate on Satellite Communication, the article puts forward the structure and design to the QPSK high-speed demodulator based on the Costas Algorithm and Gardner Algorithm. The improvement make the Lock have the characteristics of saw tooth-shaped phase detect based on the Costas Lock, which reduce the "delay" in the whole circuit. There are just 6 signals and 6 decisions in the process to get the error required. And it just needs 2 symbol decisions. The article also uses the GARDNER Algorithm which needn't decision feedback or training sets in the design of the QPSK demodulation system. The design of QPSK demodulation system has been proved the reasonability via the simulation under the parallel structure.