Based on the data from cloud-to-ground (CG) lightning detection network with 11 ADTD equipment, doppler radar, sounding, AWS data and important weather reports in Jiangxi Province during 2004-2014, severe convective weather events in these years are divided into three types: the short-time heavy rainfall, the thunderstorm gale or hail with and without short-time heavy rainfall. The characteristics of the CG flashes and their relations to radar echoes are analyzed statistically. The results show that: (1) The short-time heavy rainfall, thunderstorm gale and hail in Jiangxi occur mainly from May to August, July to August and March respectively. The stations with short-time heavy rainfall are much more than those with thunderstorm gale or hail. The thunderstorm gale or hail weather accompanied by short-time heavy rainfall often occurs in most seasons in addition to early spring and middle summer. (2) The more short-time heavy rainfall intensity is the more northern its position, and the more severe the CG flashes are. There are obvious seasonal differences of CG flash totals with different hourly rainfall: In March and April, the CG flashes are most evident with hourly rainfall of 50-55 mm, while in May, June and July, the CG flashes increase with hourly rainfall, reaching the top with hourly rainfall of 55-60 mm. In August and September, the most evident is the events with the hourly rainfall of 40-45 mm. (3) From March to May, CG flashes seen 30 min before hail without short-time heavy rainfall have no significant differences compared with those of thunderstorm gale, yet the average intensity of thunderstorm gale is higher than that of hail weather. From June to September, CG flashes in thunderstorm gales are 2-4 times more than that of hail, the average intensity of the flashes is higher than the former, and the intensity of +CGs is also slightly more intense. (4) The +CGs and -CGs with short-time heavy rainfall occurrence are separately in August and June. For the total CGs one hour before the severe weather happens, the seasonal change of that with hail is not evident, but it turns contrary to thunderstorm gales, more evident in summer than in spring. Also, there is a positive correlation between the hail CG flash totals and hail diameters. (5) From March to August, the CG flashes of thunderstorm gale or hail accompanied with short-time heavy rainfall are much higher than that without short-time heavy rainfall, while the average intensity of the former is much higher than the latter. (6) Before the severe convections take place, the negative CG flashes frequency is more evident than the positive one, but its intensity is lower than the latter. The higher the echo of reflectivity above 45 dBz extends, the more the CG flash totals are, but the average intensity change is not obvious.