Abstract: In this paper, the kinetic energy balance for a landed typhoon labelled 8116 and its environment as well as the external heavy rain area has been diagnostically examined. The results show that the kinetic energy production term is the major energy source in all the three regions, while the kinetic energy horizontal divergence term and the friction term are the major sinks. The increase of kinetic energy in the external heavy rain area is closely connetted with the typhoon weakening process. The horizontal divergence at the upper level of the typhoon displays asymmetrical distribution. A subsynoptic-scale strong wind band at the right flank of the typhoon plays important roles in transporting the kinetic energy into the external heavy rain area and stimulating the development of the heavy rain. Since the occurrence of heavy rain the typhoon kinetic energy was transported into environment through the north boundary of the heavy rain area, so that the kinetic energy dispersed from the typhoon would be finally transported into the environment. This kinetic energy transporting process in associated with the interaction between typhoon and its environment seems to be one of the mechanisms leading to the decay of the typhoon.