A Severe Convective case occurred at the rear of northeast Cold Vortex (SCCV) on May 14, 2017, in the Yangtze Huaihe region, which caused short-term intense precipitation, hail and high wind. The ensemble Kalman filter technology is used to assimilate the radar radial wind, radar retrieved wind, GPS water vapor data, radiosonde and hourly surface observation data. Observation and simulation results demonstrated the impact of Dabie Mountains on the development of the SCCV. When the SCCV moved closer to the Dabie Mountains, local convections initiated in the northern Dabie Mountains and strengthened twice subsequently. When the SCCV moving southward, its cold pool flowed to the topography and then uplifted. The solar radiation heating led to the unstable stratification on the Dabie Mountains. The two processes triggered the local convection in the Dabie Mountains. Several local convective cells initiated successively in the Dabie Mountains. The cold pool of the SCCV superposed to that of dissipating cell, leading to cold pool reinforcement, which then promote the development of new cell, and this is the first strengthening process. The second strengthening process is the result of boundary layer uplift, thermal effect of the Dabie Mountains and cold pool. When synoptic scale system moving southward, the boundary layer frontal zone (850hPa and 925hPa) moved southward and overlapped with the outflow of surface cold pool, which enhanced the boundary layer uplift. Simultaneously, the thermal heating in the Dabie Mountains in the afternoon formed thermal uplifting on the one hand, and formed the upslope wind on the southern slopes of the Dabie Mountains on the other hand.