Provided is a pressure sore risk assessment method and system based on near-infrared spectrum muscle oxygen content measurement. The method includes the steps of (1) in a resting state, monitoring the muscle oxygen parameter content of a pressure sore risk area; (2) applying 10-30 kPa of pressure for 1-10 minutes to the pressure sore risk area; (3) after pressure interruption, measuring the muscle oxygen parameter content of the pressure sore area for 5-15 minutes; (4) processing the muscle oxygen parameter content signals collected by step (1) and (3) to show the risk probability of the occurrence of pressure sores. According to the pressure sore risk assessment method and system, the muscle oxygen content can be non-invasively detected, and the equipment has good portability, which facilitates real-time monitoring.