Using the Penn StateNCAR nonhydrostatic mesoscale model (MM5), the later per iod of landfall of typhoon Matsa is simulated. A lowpass filter is used to sep arate the flow into a larger and a subsynoptic scale component. Then the sub synoptic scale features of Matsa were investigated based on movable coordinate. From the view of the effect of terrain on the interactions between two scales, t he influence of terrain on tropical cyclone is proved to be nonnegligible furt her. The results are as follows: The existence of terrain helps to maintain the intens ity of tropical cyclone and the effect intensifies with the minishing of distanc e between the corner of cyclone and terrain. The intensification is more evident at upper troposphere. At low level the subsynoptic system converts smaller kinetic energy into tropical cyclone and gets more kinetic energy from tro pical cyclone if terrain is taken out. Meanwhile, the su bsynoptic system gets more positive vertical vorticity from tropical cyclone. In a word, tropical cyclone dos not get but losses positive vertical vorticity i f without terrain.