Abstract：The study was carried out on the landfall typhoon 0515 Khanun which affected East China seriously. Firstly, based on the characteristics of large-scale circulation and physics factors, the causes of the quick strengthening, which came ahead of its landfall, were analyzed. The results show that the enhancement of intensity was associated with lower layer moisture transportation, upper level strong divergence, and the typhoon moving to where vertical shear was low and sea surface temperature was high. Secondly, focusing on horizontal stream field, the structure of warm core, the stability and vorticity, and the landfall intensity were comparative analyzed between typhoon Khanun and Rananim. It is found that Khanun was weaker than Rananim in these aspects; this conclusion may serve as references on judging the landfall intensity of typhoon.