Based on daily meteorological data from 62 stations from late July to early September during 1981 to 2018, and the meteorological industry standard Temperature Index of High Temperature Harm for Main Crops, the single-station and regional disaster-causing index of single-season-rice heat injury were divided. According to the regional index, three provincial grades were classified: i.e., light, medium and severe. In addition, the variation of single-season-rice heat injury in Anhui Province in the recent 40 years was analyzed. The results show that, the coincidence rate of historical test of disaster grade reached 97%. It can be used to quantitatively evaluate the effect of heat injury on single-season-rice in the whole province or in a region. Thus, this index can be applied to the operational services of single-season-rice yield prediction and disaster assessment in Anhui Province.