Abstract: After keeping the nuptial flight of Reticulitermes chinensis Snyder under biological observation for eight years in Chengdu, Yibin, Leshan and Chongqing, it is considered that its nuptial flight may be divided into the start, peak and end stages. It can be seen from analysis of climatic factors that suitable air temperature is important for the nuptial flight. The early or late peak stage is interrelated with the 40 days of continuous accumulated temperature in the regions mentioned above before the 25th of March in the year. As air temperature is the main cause for nuptial flight and Sichuan Basin is a special climatic region, the peak stages of the nuptial flight in those regions occur within the same month and ten days; of the year and all the days of peak flight are mainly between the initial flowering phase of Robinia pseudoacacia L. in Yibin region and the heavy withering phase in chengdu region, therefore, the peak stages of nuptial flight in Chengdu and Chongqing regions can be predicted merely by the accumulated temperature of Chengdu or the phenological phase of Yibin and Chengdu.