Abstract: The channel 1 and 2 of AVHRR on NOAA polar orbit satellites have no on-board calibration capabilities. Therefore, a methodology is developed to make comparison analysis on the data measured by NOAA-9 and NOAA-10 by using the earth surface with neglectable seasonal changes as the target area. A statistical method to normalize NOAA-9 data to those of NOAA-10 is presented.