Abstract: Using the band-pass filter and composite analysis in a temporal domain,quasi-40 day and quasi-biweekly oscillations for the OLR data in summer months of 1981 are compared to show that: (1) there are quasi-40 day and biweekly oscillations throughout the South Asia monsoon region, which affect the active/break of the monsoon ; (2) the OLR distribution from East China to the area of Japan is of opposite phase to that from the south China Sea to West Pacific, indicating that the tropical southwest monsoon will not move over the East Asia continent to bring there strong monsoon rain unless the monsoon trough breaks in the South China Sea; (3) OLR is so distributed that the active/break for the monsoon rain over the East Asia continent and the northern Indian plain is in phase with the quasi-40 day oscillation but of opposite phase to the quasi-biweekly oscillation ;and (4)the transition of the active/break for the monsoon rain in the East Asia continent and the quasi-40 day oscillaiton are caused by a northward-going part dissociated from a disturbance in the South China Sea, while the quasi-biweekly ossillation is resulted from regular eastward movement of the monsoon disturbance over the northern Indian plain.