Based on the CFS reanalysis data with spatial resolution of 0.5×0.5 degrees, we conduct a census of the Southwest Vortex from May to October in 2004—2017 after making a quality test to CFS and TMPA V7 data. According to the precipitation distribution shown by TMPA V7 data, we classified Southwest Vortex. The frequency of the precipitation in different directions is counted, and the precipitation characteristics of the four most types are analyzed, including the range of rainstorm and the intensity of precipitation. The circulation differences as well as precipitation formation mechanism of the four representative cases are analyzed. The results show that, there is a consistently growth in the amount of Southwest Vortex through these summer half years. Moreover, the southwest vortex precipitation frequently occurred in the northeast, east, southeast and central parts of the southwest vortex successively in the summer half year. Analysis of four kinds of frequent frequency southwest vortex precipitation characteristics. It is found that precipitation in central section has the largest average range of rainstorm and the strongest precipitation intensity, followed by precipitation in southeast part of southwest vortex, east part and northeast part successively. Through the analysis of circulation situation on representative case, we found that, both in the type of central part and northeast part precipitation, cold and warm currents meet in the northern part of the basin. The difference is that central part precipitation occurs when there is a wider range of cold air intrusion at the low level and the southwest airflow is stronger compared with the type of northeast part precipitation. These two branches form a circular flow field in the basin which is different from confrontation state happened in the type of northeast part precipitation. The type of east and southeast part precipitation happens when there is no cold air invasion. The last one happens when the southwest current turn westward in front of Daba Mountains. However, the former one happens when the current flows eastward compared with type of southeast part precipitation and finally flows across Daba Mountains. The formation mechanism of four kinds of Southwest Vortex is analyzed. It is found that there is a significant vertical circulation in Southwest Vortex. The circulation circle is usually composed of an ascending airflow near the southwest vortex and a downdraft of the north side. The precipitation area is usually corresponding to the position of the circulation circle.