Taking pan evaporation paradox as a key scientific assumption, this study collected and analyzed daily meteorological data from 588 rain stations over China using FCM regionalization method and Modified Mann-Kendall trend test. The results indicate that: 1) China is divided into 3 homogeneous climate regions with the help of FCM algorithm of fuzzy clustering: East-middle-south region (the south, middle, southwest and east China); West-north region(the northwest China); A long and narrow strip between the cluster a and b extending from northeast to southwest China; 2) significant decreasing pan evaporation can be found in southern,central, southwestern, eastern and northwestern China. Stations with significant increasing pan evaporation seem to be distributed sporadically across China. Besides, the strip zone extending in the NE-SW direction is dominated by significant/non-significant increasing trends of pan evaporation; 3) Sensitivity analysis indicates that relative humidity is the principal influencing factor for pan evaporation. Generally, in northwestern,northern and northeastern China, relative humidity has an adverse relation with pan evaporation, implying pan evaporation paradox in China and also intensifying hydrological cycle in these regions. In southeastern China,particularly the middle and lower Yangtze River basin and the Pearl River basin, relations between pan evaporation and relative humidity are relatively complex, showing that more factors than relative humidity can have impacts on pan evaporation changes, such as cloud coverage, temperature and aerosol concentration. Local features of aerodynamic and radiative drivers of the hydrological cycle and their regional responses to climate changes, and also different features of underlying ground may play considerable roles in pan evaporation changes.