Abstract: With the 191 stations observation data and the NCEP/NCAR reanalysis data, a diagnosis is carried out for the abnormal high temperature event over Mid-East China (MEC) during 2013. The results show that the temperature anomaly is mainly associated with the abnormal diabatic heating (sinking motion), although the diabatic heating (net long wave radiation flux) was an important process contributed to the warming during summer over MEC. The corresponding weather pattern analyses indicate that the extreme intensity, northward and westward extension of the Western Pacific subtropical high (WPSH) and extreme intensity and northward extension of the 200 hPa South Asian high are the main reasons for the strong sinking motion over MEC. The strong sinking motion reduces the clouds and rain therein with the surface obtains more solar radiations. With the surface temperature increasing, the diabatic heating (upward sensible heat flux and upward longwave radiation) are increased. The analysis of the sea surface temperature shows that the extreme intensity, northward and westward extension of the WPSH is mainly caused by the unusually high SST in the equatorial western Pacific,the westerly wind drift region and the Kuroshio Current area.