The fog days in Henan Province from 1961 to 2005 are analyzed. The resu lts show that the yearly averaged number of fog days is more in autumn and winte r than in spring and summer, fog mainly appears in November to January of the ne xt year. The spatial distribution is very uneven and shows the trend of increase from east to west and from basin to hills. There are 5 fog centers in Henan pro vince. 40 stations are chosen for analyzing by using EOF. The results show that the first 3 modes account for 76.5% of the total accumulative variance contribution. The analyses on the correlation coefficient and the time coefficient of th e 1st mode indicate that the fog days in most areas in Henan province is increas ing, which is the same as the trend of temperature variation. Wavelet analysis i ndicates that fog days have periods of 2-4 years, 8-10 years and 19-22 years. Th e 500hPa anomaly height fields in morefog years and in lessfog years are exa mi ned. It shows the anomaly height fields of the middle and high latitude in Europ e and Asia are opposite, and display +-+ mode in more -fog years, and -+- mode i n lessfog years, respectively.