The abrupt recurved severe typhoon Chanchu and its inner core structure evolution are documented by using FY2 TBB images, NCEP final analysis and the new generation mesoscale weather research and forecasting (WRF) model. Results show that the surrounding largescale steering flow and potential vorticity tendency play important roles in Chanchu movement. The rightward deflection of Chanchu is indicated by the surrounding largescale steering flow in advance. Chanchu is likely to move toward an area of maximum wavenumber1 potential vorticity tendency. The evolution of inner core asymmetric structure is closely related to the environmental vertical wind shear. The shearinduced tilt of the vortex has a dominant influence on the maximum upward motion in the southerly quadrant of Chanchu.