Based on the observation data of the global solar radiation between Holland CM6B and Domestic Instrumemts at the same time. Using the statistical analysis method, the collected data from two sets of instruments are analyzed, and the possible reasons for the differences are discussed. The results show that: the observed data from the domestic instrument and Holland CM6B pyranometer have small differences. The average daily value is 013 MJ〖DK〗·m-2, and the difference of standard deviation is 075 MJ〖DK〗·m-2. The monthly accumulative global solar radiation differences between two sets of instruments have obvious seasonal characteristics. The spring and summer differences are slightly higher than those of autumn and winter season; the overall variation shows a gentle trend; and all the data are appliacable. The domestic global solar radiation is more reliable. The differences in manufacturers, models, parameter sensitivity, the errors of calibration, and manual correction data are the main reasons for the significant difference between two sets of instrument.