In the paper, the low temperature and steadily rainy synoptic process is defined based on temperature and precipitation data. It is discovered that the tropical circulation and spectrum features in the process of steadily rainning varies significantly from that of steadily shining. The distribution of total cloud cover on the section of 156°E is obviously differents from that of 180° in the tropical Pacific. In addition ,the El Nino year has got a relationship much closer with the steadily rainning weather in the middle and lower reaches of the Changjiang River .