Abstract: By utilizing elative humidity of the Xichang observatory during the parallel observation period of both manual and automated station from January 1,2007 to December 31,2007,the analyses are made on the differences between manual-observed and automatic-observed relative humidity data in different time scales of day,month and different weather conditions,and establish the corrections equation and variance analysis.The results indicate that correlation coefficient of manual and automatic station daily relative humidity between.0.826-0.998;Observed values of relative humidity is always higher than the automatic observations,comparing the average daily range from 2.27% to 8.79%,compared the average difference of 5.25%;Monsoon rains and poor dry season with 5.32% 4.90% respectively;Times average value of obvious contrast,minimum value at 19,for 4.36%,maximum difference at 12:00,for 6.34%;Different weather conditions of relative humidity is different,the comparison of difference in 2007 99 sunny contrast value range is average for 7.66%-4.91%,5.66%,30 cloudy contrast value range 4.29%-6.52%,average for 5.32%,118 rainy contrast value range is 4.22%-5.16%,average for 4.88%;Respectively established in 2007,sunny day,month relative humidity,rainy days month relative humidity,and revised equation analysis of variance,the establishment of 48 corrections equations are through 0.05 level,correction effect is obviously.Manual and automatic station caused by the reasons for the differences of relative humidity is:observation time,wet ball gauze and water,artificial readings,weather conditions,etc.