Three typical long duration torrential rain events in Liaoning Province are selected. Based on the data of NCEP/NCAR 1°×1° reanalysis, FY2E black body temperature (TBB for short), Doppler weather radar and automatic weather station, the representative characteristics of changes in precipitation observation, the background of synoptic situation, the satellite infrared cloud image, the structure and intensity of radar echoes are analyzed. The results show that long duration torrential rain that occurs in Liaoning Province are caused by longterm continuous interaction of warm and cold air masses in certain areas under the background of largescale synoptic environment conducive to torrential rain. This type of torrential rain has two types of characteristics. One is little change in precipitation intensity, and no obvious periodical characteristics of torrential rain, and the another is strong change in precipitation intensity, and obvious periodical characteristics of torrential rain. The general convective clouds, warm clouds and deep convective clouds can cause torrential rain, in which the TBB of general convective clouds varies between -47℃ and -36℃, the TBB of warm clouds is between -8℃ and 3℃, the TBB of deep convective clouds is between -68℃ and -50℃, and torrential rain occurs in the center of the low TBB to the large temperature gradient zone on one side. This type of torrential rain shows that the upper stream radar echoes continuously move into the downstream to form a “train effect”, the locally generated and intensified strong echoes and the strong radar echoes generated from the upstream maintain intensities and step into the downstream. The hourly average radar echo intensity and its change have a good indication of precipitation intensity and its trend. In particular, special attention should be paid to the analysis and monitoring of warm cloud which contributes to torrential rain in the west side of the subtropical high, high energy and high humidity, low condensation height, the whole almost saturated layer, and the trigger conditions of local topographic uplift.