Abstract: This paper reviews the Global Position System (GPS) satellite signal first, and then introduced the Software Define Radio (SDR) into Global Navigation Satellite System (GNSS) receiver. It also presents the development of a new kind of GNSS receiver, which is upgradable, highly flexible and multi-system compatible. In order to apply it on the Micro-Satellite Platform (MSP), the hardware system was made up of Field Programmable Gate Array (FPGA) and Digital Signal Processor (DSP). The software structure is also presented. In the end of the paper, the advantage and disadvantage of the software GNSS receiver applied in MSP are given, and the future of this GNSS receiver is discussed.