The intra srasonal oscillation of the atmosphere (ISO) mainly indicates the oscillation at a time scale of 30 to 60 days, one of the most remarkable oscillation phenomenans. As one of the most distinct low frequency systems, ISO has been paid great attention widely, and already obtained numerous meaningful results since the 1970s. ISO plays a crucial role in adjusting climate variability and influences weather and climate of China profoundly. A systemic summary is made of the researches on ISO in the recent years, with emphases on its structure, activity characteristics, influence on weather and climate, stimulation, and maintaining mechanisms. The prospects of further studies about ISO are discussed based on those summaries.