Abstract: To study the influence of heat resource change on cotton yield and key period in Shihezi reclamation area of Xinjiang, we collected various data, such as cotton per unit yield and temperature from 1961 to 2015, and the monitoring data of cotton phonological period from 1988 to 2017. We studied the contribution of heat resource to cotton yield in different time periods by means of polynomial separation of the climate yield, climatic tendency rate, simple regression and correlation coefficient analysis and so on. The results showed that: there was a significant increasing trend of heat resource in Shihezi reclamation area; the cotton yield was significantly influenced by the accumulated temperature of ≥10℃, the cotton production period accumulated temperature of ≥0℃, temperature stability through 10℃ both on the first day and last day, the accumulated temperature of ≥10℃ in the sowing and seedling stage and the period from cracked to the end of the growth; what’s more, the reduction of cotton yields was significantly influenced by the accumulated temperature of ≥ 10℃ lower than 3350℃·d, the cotton production period accumulated temperature of ≥0℃ lower than 3650℃·d; the sowing and seedling stage and the period from cracking to the end of the growth were the critical periods of the cotton heat, and their contribution to the cotton yield was 6.59% and 5.95%, respectively. The results can improve the technical management of cotton production in Shihezi reclamation area of Xinjiang.