Spinal cord lesions can cause a series of severe complications, which can even lead to paralysis with high mortality. However, the traditional diagnosis of spinal cord lesion relies on complicated imaging modalities and other invasive and dangerous methods. Here, we have designed a small monitor based on NIRS technology for noninvasive monitoring for spinal cord lesions. The development of the instrument system includes the design of hardware circuits and the program of software. In terms of hardware, OPT1011 is selected as the light detector, and the appropriate probe distribution structure is selected according to the simulation result of Monte Carlo Simulation. At the same time, the powerful controller is selected as our system’s central processing chip for the circuit design, and the data is transmitted by serial port to the host computer for post processing. Finally, we verify the stability and feasibility of the instrument system. It is found that the spinal signal could be obviously detected in the system, which indicates that our monitor based on NIRS technology has the potential to monitor the spinal lesion.