Abstract:General circulation features over the Northern Hemisphere in 2004 are analyzed. In the first half year of 2004, the atmosphere and ocean in the central and eastern Pacific near equator tended to be a normal state. From July 2004, SST in the equatorial middle and east Pacific became warmer than before. Subtropical high over the west Pacific Ocean continued to be strong in 2004. It located eastward to its normal position and the ridge line was northward to its normal value in summer. In the first and second dekad of June, the geopotential height was higher than its normal value over the west of Baikal. In the second dekad of July and August, the geopotential height field was higher than its normal over Baikal. The South China Sea summer monsoon outbreaked in normal time and the South Asia summer monsoon was stronger than normal. The 500hPa potential high over Tibetan in 2004 was higher than normal and the snow cover was more than normal. The convection over the warm pool was more active in the second half year than that in the first half year in 2004. The climate anomaly in 2004 was possibly caused by the SST anomalies of the tropical Pacific and atmospheric general circulation.