Abstract: Using the comparative observation data of 2 400 national stations in China during the second year of automatic and artificial parallel observation period, as well as all rainfall observation data of base stations from 1999 to 2010, the difference between automatic and artificial observation rainfall data are compared and analyzed. The significance of the rainfall data series of the base station was tested. The results are as follows. (1) There is a certain difference between automatic and artificial rainfall data. The automatic observation data are slightly larger than manual observation data. The average relative difference is 1.8. (2) The average monthly precipitation difference between the two groups is between -1.33.9 mm and -1.33.9 mm. When the precipitation grade increases, the difference between the two is not the same proportion. (3) The maximum monthly relative difference between them is 2.9 and the minimum relative difference is 0.8. (4) The spatial distribution of the relative difference between the two shows that the deviation between May and September is slightly higher than that in July. (5) The significance test of the automatic monthly rainfall in the second year of parallel observation period shows that, at the significant level a=0.05, the unpassed rate of monthly rainfall at national stations was 2%.