The influence of non-uniform distributions of thermochemical parameters on the sooting flame measurements was comprehensively studied via the line-of-sight （LOS） dual-color laser absorption spectroscopy （LAS） in flame thermometry. Six representative absorption line pairs of water vapor （H₂O） within the wavelength range of 1.3-3.0 μm were selected as optimal for the investigations. High-fidelity spectral simulations were performed to investigate the influence of the non-uniform temperature and concentration distributions on sooting flames with nitrogen and air co-flows. The non-uniformity conditions for sooting flames with nitrogen co-flow and sooting flames with air co-flow were abtained. For sooting flames with nitrogen co-flow， the maximum temperature deviations of the spectral line pairs （4 029.52 cm^-1/4 030.73 cm^-1 and 5 553.86 cm^-1/5 554.18 cm^-1） were observed to be the smallest （i.e.， 4.72%） and largest （i.e.， 12.40%）， respectively. For sooting flames with air co-flow， the temperature deviations exhibited positive and negative values， with the maximum positive and negative values observed under the non-uniformity condition of δ/L=80%. In particular， the maximum positive and negative temperature deviations were 14.43% and -2.51% for the line pair 5 553.86 cm^-1/5 554.18 cm^-1， and 3.22% and -13.21% for the spectral line pair 4 029.52 cm^-1/4 030.73 cm^-1. The numerical simulation results were subsequently compared with experimental measurements using the line pair near 4 029.52 cm^-1/4 030.73 cm^-1. The experimental results indicated that， in two typical sooting flames， the line pair 4 029.52 cm^-1/4 030.73 cm^-1 can effectively mitigate the influence of non-uniform distributions of thermochemical parameters on the temperature measurement.