Abstract: Based on mean sea level pressure (MSLP) data, the East Asian winter monsoon intensity indexes were calculated from 1873 to 1990. The sudden and periodic changes of East Asian winter monsoon were studied by the method of sliding t-test and singular spectral analysis (SSA). The results show that East Asian winter monsoon intensity displays obvious interannual and interdecadal variations. When winter monsoon increases, the temperature in the most regions of China decreases. Mongolian high raises and Aleutian low deepens, and reverse in weak winter monsoon year. Meanwhile, East Asian winter monsoon shows quasi-biennial oscillation (QBO), low frequency oscillation (3~7 years) and interdecadal oscillation (more than 10 years). These three periodic oscillations appear to have strong interdecadal variability.