Abstract: Using new formulae of moist available energy (MAE), the typhoon T8108 was studied and its three components of MAE during the various periods were calculated. The results show that the system of typhoon has a high energy, its MAE in the stage of the extratropical cyclone is more than that in the stage of the tropical typhoon. The changes of MAE is mainly due to the variance of barotropic and baroclinic components. And different energy characteristics appear in different periods of typhoon rain. The expenditure of energy for the typhoon rain is mainly from the baroclinic component, and stratification component in the lower troposphere