In order to investigate the reliability of total atmospheric water vapor data from L-band radiosonde observations (RS PW), the atmospheric water vapor of GNSS/MET remote sensing (GNSS PW) is taken as the reference standard in this paper to comparatively analyze and correct the observed RS PW at Shantou Station in 2013 and Nagqu Station from June 2016 to May 2017. Research and analysis show that RS PWs at the two stations are obviously smaller than GNSS PW, and the deviations are 7.4% and 9.8%, respectively. The deviation has obvious seasonal and diurnal variation characteristics. In summer it is most obvious, and is more obvious at 0000 UTC than at 1200 UTC. Solar radiation heating and air temperature changes in the daily and seasonal variations are important reasons for the deviation. According to solar radiation bias correction formula, the L bias correction algorithm is proposed and used for correction. Then the deviation is reduced obviously after correction.