A multi-processor system and a dynamic power saving method thereof are provided. The multi-processor system includes a plurality of processors and a chipset. Each of the processors has a plurality of standard bus request pins and a specific bus request pin, and the standard bus request pins of each processor are alternately connected to the standard bus request pins of other processors respectively. The chipset is coupled to the specific bus request pins of the processors for detecting a control request signal on the specific bus request pins. When the chipset detects the control request signal, the chipset turns on an input buffer connected with the processors so that the processors can access data through the input buffer. When the chipset does not detect the control request signal, the chipset turns off the input buffer.