Tunable diode laser absorption spectroscopy (TDLAS), as a robust non-contact measurement technology, has exhensive applications in the diagnosis, for harsh environments commonly experienced in combustion and propulsion flows. A tunable diode laser sensor, which is based on water absorption, has been developed to measure temperature and velocity in a supersonic ground-test facility simultaneously. Scanned-wavelength direct absorption spectroscopy and calibration-free wavelength modulation spectroscopy are employed to enable the absolute measurement. The sensor is tested at the direct-connect supersonic combustion facility which operates at mass flux of 2.5 kg/s, Mach number of 2.0, total pressure from 5.3 to 5.7 atm (1 atm=1.01325×105 Pa) and total temperature from 1100 K to 1700 K. The measured temperature and velocity agree well with the theoretical model, which validates the efficiency of the sensor design. The investigative results can provide the technique support for engineering applications.