Temperature is one of the important parameters to measure the combustion efficiency. The measurement of temperature is of great significance for saving energy and reducing emission in industrial combustion process and diagnosing the engine state. The tunable diode laser absorption spectroscopy is a non-invasive measurement technology with strong environmental adaptability for fast, in-situ detection. Based on the three absorption lines of H₂O at 7185.6 cm^–1, 6807.8 cm^–1 and 7444.35/37 cm^–1, the wavelength modulated spectrum absorption model is established and laboratory-calibrated; using the background-subtracting WMS-2f/1f method and the best fit method, the temperature is measured. The outlet temperature of the single-head combustion chamber is accurately realized. The outlet temperature of the single-sector combustion chamber is also accurately measured. The measurement is verified in a pressure range of 3.39－10.58 atm and a temperature range of 958－1512 K. The time resolution of the measurement system is less than 1 ms, and the measurement error is less than 5.68%, thus verifying the practicality of the measurement method and the stability of the measurement system.