In order to measure the Oxygen mass flow rate effectively, the absorption of Oxygen molecules around 13 144.5 cm－1 was studied based on the principle of laser Doppler frequency shift, combined with wavelength modulation spectroscopy and tunable diode laser absorption spectroscopy technology. An experimental system was built for supersonic air mass flow measurement based on the wavelength modulation and tunable diode laser absorption spectroscopy technology. The airflow velocity and Oxygen concentration were retrieved according to the frequency shift and the peak value of the second harmonic signal of O2 molecular. The experimental results indicate that, in the laboratory environment, the airflow velocity of the system is 707.6 m/s, the Oxygen concentration is 0.49 g/L and the mass flow rate is about 0.42 kg/s, with a measurement error of 5.46%.The experimental results can be used in Oxygen mass-flow of engine inlet measurement system miniaturize development and flight experiment by TDLAS.