A severe typical warm sector torrential rain with the obvious mesoscale characteristics of long lasting and concentrating precipitation area attacked Huanghuai Region on July 7 2012. The formation of the warm sector torrential rain induced by the Huanghuai warm wind shear line is discussed based on conventional and unconventional observation data and NCEP analysis data. The results showed that the whole troposphere with high humidity is beneficial to weaken the lifting condition, enhance precipitation efficiency and formation of quasi stationary mesoscale convective systems. Vertical wind shear in low troposphere and extra low altitude jet flow are likely to play an important role in triggering and maintaining the convection. Subsynoptic and mesoscale lift conditions such as surface wind convergence line, shear line at 850 hPa or 925 hPa and wind convergence brought by the low level jet can lead to the torrential rain. Meanwhile, the radar echo represents the backward propagation, train effects and tropical heavy rainfall characteristics.