Abstract: Based on the meteorological data from 36 stations in 2006 in Inner Mongolia, air temperature, pressure, relative humidity and wind from automatic and manual observation stations were compared and evaluated. The differences between automatic and manual observation data, the standard deviations of the differences, frequency and spatial distributions of the differences were analyzed in order to discuss the reasons causing the differences. The results indicate that there exist the differences between two observation systems for most meteorological elements. However, the differences are acceptable and in the range of allowable error of automatic observation station. The reasons forming the difference between automatic and manual observation data include the differences of instrument structure, observation theory and methods, observation time and space. In order to ensure the continuity of data, the manual observation data must be revised according to the local truth if the automatic and manual observation data are used together in a study.