Based on the T213 numerical prediction products and the routine radiosonde and surface observation data, the development and movement of the typhoon Chanchu (No.0601) are studied by means of the GRAPESbased numerical experiment. The results show that the GRAPES model has a good ability to forecast the intensification, moving track, and heavy rainfall caused by Chanchu. This model simulated out well the landing spot and especially the track of Chanchu, which made an abrupt clockwise turning from west to north in the central South China Sea. By analysis of the 500 hPa geopotential height and the sealevel pressure fields, as well as temperature, vertical motion and vortex, it is showed that the abrupt turning of the track was related to the adjustment of the general circulation, the movement of cold air, and its own dissymmetrical structure.