Aiming at the problem that test safety and data quality will be serious impacted if shock wave falls back to test section in supersonic wind tunnel, the real time monitoring system based on shock wave position is designed. The data acquisition system based on Ethernet was designed, software function and characteristics were introduced and the wind tunnel test results were presented. The test results show that the system is stable and credible. It is provided a new method to ensure the test safety and data quality. Meanwhile, it is also useful in optimization running parameters and fixing on requirement of percentage of blockage in every mach number.