The Qing Dynasty was the peak of epidemics in Chinese history, and the Qianlong era was one of the important periods. The study achieves several results. (1) There were 58 years out of the entire Qianlong era recorded with epidemic disasters, which produces a frequency of 96.67%. Among the disasters, three large-scale epidemics in 1748, 1756 and 1786 were superimposed to form a fluctuating upward epidemic trend. Epidemics mainly took place in summer, followed by spring and autumn, and much less in winter. (2) At the provincial level, there were two separate zones of high epidemic index in the South and the North, and the epidemic index gradually increased from West to East. Jiangsu Province (including Shanghai) was the most badly affected. At the county level, the distribution of epidemic disasters had stage characteristics, and the scope of affected areas was expanding. The distribution pattern of epidemic disasters has the characteristics of agglomeration, and its degree tends to increase. It also has regional variance, but the epicenter is always in the South (3) The distribution pattern of epidemic disaster during the Qianlong era correlates with population distribution pattern, regional development intensity and natural disasters, which shows a significant positive correlation with epidemic disaster intensity at provincial level, with R values of 0.886, 0.664 and 0.685 respectively (P=0.01).