Abstract: Using NCEP/NCAR R2 reanalysis daily data and the daily meteorological observational data in Southwest China from 1979 to 2012，the main submonthly timescales of the East Asian winter monsoon and its oscillation characteristics are studied by the wavelet transformation，bandpass filtering，composite analysis and correlation analysis in this paper．The main conclusions are:The East Asian winter monsoon has quasi－week period，quasi－two－week period and quasi－three week period variability，the intensity of quasi－two－week period is slightly stronger than quasi－week period and quasithree week period variability．There exist obviously negative correlation between the East Asian winter monsoon and the winter temperature in Southwest China on submonthly，quasi－one－week and quasi－two－week time scales．The oscillation characteristics of East Asian winter monsoon on submonthly，quasi－one－week and quasi－two－week time scales is important to the medium and long range prediction of low－temperature process in Southwest China．