Abstract: Using conventional meteorological observations and numerical models of T639 and EC data,rainfall in large area occured on June 27,2012 in Wuhai for pattern test diagnostic was analyzed.The results showed that loop cyclone moved under the guidance of Vice-high perimeter southwest jet to the northeast,caused by the direct impact of rainfall systems, heavy rainfall occured in the eastern side of the symmetry axis of the vortex 700 h Pa,southwest jet provided for the occurrence of abundant rainfall water vapor and potentially unstable energy;changes in the lower troposphere vorticity advection and temperature advection is the main factor affecting the development and movement of the vortex,abundant moisture transport from the south of the Yellow River is the main reason for the maximum precipitation occurring.EC and T639 models of the precipitation forecast results were basically same.Through analysis of heavy rainfall of summer in Wuhai Numerical test diagnostic, it is summarized effective methods and models to examine the effect of Wuhai weather forecast heavy rainfall.