Line-of-sight tunable-diode-laser absorption spectroscopy(LOS-TDLAS) with multiple absorption lines is introduced for non-uniform temperature measurement. Temperature binning method combined with Gauss–Seidel iteration method is used to measure temperature probability distribution function(PDF) along the line-of-sight(LOS). Through 100 simulated measurements, the variation of measurement accuracy is investigated with the number of absorption lines, the number of temperature bins and the magnitude of temperature non-uniformity. A field model with 2-T temperature distribution and15 well-selected absorption lines are used for the simulation study. The Gauss–Seidel iteration method is discussed for its reliability. The investigation result about the variation of measurement accuracy with the number of temperature bins is different from the previous research results. Line-of-sight tunable-diode-laser absorption spectroscopy (LOS-TDLAS) with multiple absorption lines is introduced for non-uniform temperature measurement. Temperature binning method combined with Gauss-Seidel iteration method is used to measure temperature probability distribution function Through 100 line-of-sight (LOS). Through 100 simulated measurements, the variation of measurement accuracy was investigated with the number of absorption lines, the number of temperature bins and the magnitude of temperature non-uniformity. A field model with 2 -T temperature distribution and 15 well-selected absorption lines are used for the simulation study. The Gauss-Seidel iteration method is discussed for its reliability. The investigation result about the variation of measurement accuracy with the number of temperature bins is different from the the previous research results.