The invention relates to a system and a method for measuring pulse blood oxygen. The system comprises N pulse blood oxygen sensors (11), an upper computer measurement module, a signal transmission line and a lower computer measurement module, wherein the lower computer measurement module comprises a microprocessor (15), an analog digital conversion module (14) which is electrically connected with the microprocessor, a light source driving module (17), a communication interface and shift switches (12), the shift switches are electrically connected with the N sensors, a photoelectricity amplifier module (13) and the light source driving module, one of the N sensors is selected to be communicated with the photoelectricity amplifier module (13) and the light source driving module under the control of the microprocessor, and an output end of the photoelectricity amplifier module is electrically connected with the analog digital conversion module. The method includes that by means of the lower computer measurement module, the N pulse blood oxygen sensors are driven and monitored in a time-sharing mode, N ways of measurement signals and characteristic parameter values are sent to the upper computer measurement module, and each way of the signals are processed, calculated, displayed, stored and the like.