Temperature measurement is significant for combustion diagnosis. An on-line temperature measurement method based on tunable diode laser absorption spectroscopy(TDLAS) has been developed, which achieves dual laser cooperative work and simultaneous measurement of two absorption lines (7154.35 cm-1 and 7467.77 cm-1) of combustion product H2O by dual beam time dividing scanning strategy. The accurate inversion of the temperature is realized by two-line integral absorbance ratio, which meets the application needs of on-line temperature detection of the combustion field. The experimental research on real-time detection of flame temperature in CH4/air premixed flame furnace was carried out, and the results were compared with the thermocouple measurement, which shows TDLAS and thermocouples have good consistency with relative error less than 3.8%. The feasibility and reliability of non-intrusive and rapid temperature measurement of the combustion field based TDLAS technology have been verified.