A numerical experiment is conducted on typhoon Rananim(0414) by use of the PSU/NCAR non-hydrostatic mesoscale model(MM5) and verified against observations;the track,speed,and detailed mesoscale precipitation distributions are well reproduced.Based on the successful simulation of the typhoon process,the characteristics of the typhoon before and after the landfalling are analyzed in circulation patterns and dynamical and thermodynamic structures such as horizontal circulation,temperature/humidity structure,vorticity,divergence,etc.It is found that the distribution of rainfall is related to the asymmetric distribution of moisture transportation,which affects the thermodynamic structure of the typhoon to a great extent.In vertical direction,the extension of physical elements is not only low in height but also small in amount.