Because of climatic diversity in China whose latitude and longitude span more than 20◦, there are four main peanut producing areas in China. The aim of this research was to investigate the incidence of aflatoxin contamination in peanuts at harvest under different agro-environmental conditions in China and its relationship with climatic conditions. This research would provide technical support to establish an early warning mechanism for large-scale detection and would be important for reducing pre-harvest aflatoxin contamination of peanuts.