The invention provides a physical-memory-shared multi-processor communication system and a communication method thereof. The multi-processor communication system comprises a plurality of processors and a physical memory, wherein the processors send and receive data mutually; the physical memory is divided into a plurality of physical memory blocks, so that each processor has a special physical memory block; in the processors, a sending processor which sends data sends the data to the special physical memory block of a receiving processor which receives the data, and the receiving processor reads the data from the special physical memory block thereof. According to the multi-processor communication system and the communication method thereof, when the processors transmit data mutually, occupancy of a memory space can be reduced and the utilization efficiency of the memory can be improved, so that the transmission speed of the data is increased.