Based on several kinds of observed statistics and reanalysis data, the characteristics of moving-out southwest vortex from 2007 to 2017, and their effect to precipitation in central and eastern China were studied. There were 199 southwest vortices, of which 110 cases moved out of the origin in different paths. Among the 110 moving-out southeast vortices, 60% moved in eastward path, 28.2% in northeast path, and only 10.9% in southeast path. Precipitation in central and eastern China was closely related to moving-out southwest vortex. It was proved that the precipitation was heavier in regions along the Yangtze River during the life circle of eastward-vortex. During northeast-moving vortex's life time, the precipitation increased in most area of north of Yangtze River. Coincidently, the precipitation in South China was heavier when vortex moving in southeast path. The routines of centers of vortices in eastward and northeast ways were nearly parallel to the axis of their rain bands, but not coincided. The direct cause of the deviation difference is whether there is precipitation on the north side of the vortex. Study showed, without dry and cold invasion at upper air, the stronger the southerly wind on the south side of the vortex was, the more humid the air on the north side. By this time, a low-level easterly air flow on the north side of vortex center may be conducive to the air uplift and local precipitation. When dry and cold invasion existed at upper air, a low-level easterly moist air flow may arouse convective instability, and this was also in favor of precipitation on the north side.