A synoptic analysis and numerical simulation are conducted on an explosive cyclone happened on the East China Sea on 1 June 2006, in order to further understand the physical mechanisms of the cyclone explosive development. The results show that: the main influencing system on the surface is an inverse trough from the sea area around Taiwan Islands, which encountered a strong upperlevel trough over the northern coastal area of Zhejiang. The largescale upperlevel trough provided a conducive environment for cyclone development and maintenance by positive vorticity transport before the trough and the strengthening role of cold and warm advection on baroclinic instability. At the same time, a highaltitude jet provided a favorable environment for the development and maintenance of the cyclone through divergence and warm advection around its exit. The uplifting role of strong vorticity advection in middle and lower levels induced precipitation, and the latent heat release produced by water vapor condensation strengthened the development of the ground cyclone system, during which cyclone and precipitation constituted a positive feedback mechanism. The latent heat release was excited by the uplifting movement caused by the baroclinic instability before the highaltitude trough and divergence around the exit of the jet on the right side, which played an important role in the cyclone development.