The principles and the experiment for temperature and OH concentration fields measurement by LIPF is mentioned in this paper. With a tunable KrF excimer laser, the fluorescence of OH was got in a methaneair flame at the pressure of atmosphere and the structures of the spectrum were analyzed. The instantaneous temperature in the flame was also given out by LIPF, the relative error is less than 3%. The fluorescence images of OH shows the direct images of densities and the temperature fields in quality.