Abstract: In this paper, a synoptic analysis is made for the evolution process of a tropi cal depression intensification into a storm in the Beibu Bay during August 1985. It could be seen that the eddy kinetic energy was increasing and the levels of maximal vorticity and non-divergence were descending, and that the thermodyna mic structure with a warm core was forming gradually associating with the SW Monsoon in lower troposphere, which was strengthening and moving northward with its currents entrained into the storm, during the periods of initiation and intensification of the storm.The calculation of the budget of eddy kinetic energy is made for the storm Because the storm located in a mean flow with strong horizontal and vertical shear and its wind field and temperature distribution were asymmetric and because the storm had a warm core, the storm could develop from a depression by means of obtaining barotropic and baroclinic energy. Moveover, subgrid-scale processes represented by cumulus convection were providing energy for the storm.Because of the storm’ s warm core being destroyed by the colder air invading at low layer; the energy which the storm received from the mean flow couid not make enough compensation for the loss due to friction and flux divergence of geopotential energy, and the storm fell into decay.