Using the tunable diode laser absorption spectroscopy (TDLAS) technique, the average temperature along the laser path can be measured using two absorption lines. When the average temperature along the laser path is measured by using multiple absorption lines, the measurement accuracy is mainly determined by the deviation of the measured signals and the lower energy of the absorption lines. The laser with a central wavelength of 1 392.5 nm (7 181.32 cm-1) can rapidly scan four absorption lines of H2O, in which the wave number is 7 182.950, 7 182.209, 7 181.156, and 7 179.752 cm-1 respectively, and investigate the influence of different combinations of spectral lines on precision of average temperature along laser path. The experimental results show that the weight of the accuracy to the measured temperature of every absorption line can be quickly reflected from calculating the standard deviation of the measured temperature. The standard deviation of the average temperature along the laser path is less than 20 K by absorption line selection.