The gas temperature and component concentration can be measured according to the iteration using the calibration-free wavelength-modulation spectroscopy based on the tunable semiconductor laser. The parameters required in the experiment and simulation can be obtained after measuring the laser modulation parameters of two H2O absorption lines (7185.60 cm-1 and 7454.45 cm-1). Frequency division multiplexing technology is adopted to measure gas temperature and component concentration of the gas temperature field in the temperature range of 600 K~1000 K. Experimental results show that the measured gas temperature and component concentration using the calibration-free wavelength-modulation spectroscopy are consistent with the predicted values. Compared with the temperature measured by thermocouple and the component concentration measured by direct absorption spectrum method, the most relative errors are within 4% and 5%.