In order to explore the application of laser absorption spectroscopy in the non-uniform flow, a new strategy that provides quantitative measurements of gas parameters in non-uniform environments are put forward. After evaluating the range of temperature in the field and choosing the appropriate transitions whose strengths that scale linearly with temperature, the H2O mole-fraction-weighted path-average temperature and geometric path-average H2O mole fraction can be quantitatively measured. The simulated results from two-temperature and Gaussian-temperature distribution model show the availability and reliability of this method. Compared with theoretical value, the relative errors of measured results in the two-temperature distribution model are 082% and 110% while the most relative errors in the Gaussian-temperature distribution model are 09% and 36%.