Abstract: Based on conventional observation and NCEP reanalysis data, the extremeness of an explosive Jiang-huai cyclone moving northward into Yellow Sea and Bohai Sea during 2-3 May 2016 is studied. This cyclone is then compared with a cyclone during the 11-12 May 2015 at the same period in the history. Results are as follows. (1) The statistics showed that the holding time, intensity, variation of pressure, pressure gradient, the formation time and the moving speed of this explosive Jiang-huai cyclone break the record on the first ten-day period of May in the history from 1951. (2) The high-outflow jets and the low-inflow jets are coupled. Moreover, with the interaction between frontal zone and secondary circulation, secondary circulation extends and strengthens, and available potential energy released from steep frontal zone triggers explosive development of the inland cyclone. In the explosive phase, cyclone cross the sea in a proper time, which reduces energy loss and provides extra sensible heat, radiation and latent heat for the development of the explosive Jiang-huai cyclone.