Abstract: An atypical Southwest vortex (SWV) that occurred during 27 ~ 28 October 2014 and its precipitation process are investigated by means of atmospheric heating analysis. This paper focuses on the relationship between the SWV and the precipitation process. The main results are as follows: (1) the precipitation process occurred before the SWV leads to the adiabatic heating rate increase with height, which made contribute to the genesis of the SWV. (2) Convective precipitation is the main part of the precipitation related to the SWV, and the more precipitation area is mainly distributed in the east of the vortex center. (3) There is a secondary circulation develops in the mature stage of the SWV, it can not only make for better development of the SWV, but also trigger the convection in the east of the vortex center and lead to heavy rainfall.