Abstract: Based on data from NCEP reanalysis and regional radars， the moving characteristics and structural and intensity changes of land-fall STC Utor from 13 to 19 August in 2013 were diagnosed. Meanwhile， the reasons for Utor’ s sustaining in quasi-stationary after landfallwas analyzed. It was found that the low-pressure circulation of Utor after landfall maintained quite a long time in Southern China， while the center of circulation was stable from 15 to 17 August. The subtropical high was strong and the high pressure barrier was on the north of Utor.The subtropical high also expanded into the low latitudes. Utor was surrounded by the high-pressure circulation, which may be one reason to cause Utor being stable. In this period, the weakening of environmental steering flow also caused the speed of Utor being reduced. The rapid weakening of vertical wind shear was in favor of sustaining low circulation. Utor was connected closely to a vapor channel after landfall and the sufficient moisture was favorable for the development of convection. The distribution of moisture flux and moisture convergence centers affected the distribution of convection. During the quasi-stationary sustaining period, the increase of eddy kinetic energy was positive to the maintenance of circulation, which was mainly due to the enhancement of kinetic energy generation term. Moreover， the upper-level horizontal
convergence of eddy kinetic energy flux and the conversion from environmental kinetic energy also provided kinetic energy.