Based on the observation data from the meteorological stations and agricultural experimental stations in Jiangxi Province, this paper studied the change trend of the growth period of double cropping rice in the province, and, by using the indices growing degree-days (GDD), cool degree-days (CDD), and heat degree-days (HDD), the change trends of the heat resources at each growth stage of the double cropping rice in 1981-2007 were analyzed. Under the background of climate warming, the mean air temperature, mean minimum air temperature, mean maximum air temperature during the growth period of the double cropping rice all had an increasing trend, leading to the shortening of double cropping rice growth season, with the most obvious decrease of vegetative growth phase and the prolonged reproductive growth phase. In the vegetative growth phase, the GDD and HDD increased, while the CDD decreased. In 1981-2007, the effective heat resources of double cropping rice in Jiangxi Province increased, low temperature risk reduced, while high temperature risk increased. The increment of the effective heat resources for double cropping rice was higher in northeast Jiangxi than in southwest Jiangxi, low temperature risk was higher in south Jiangxi than that in north Jiangxi, and high temperature risk was the highest in middle Jiangxi.