Abstract: Using serial statistical data, this paper discussed the spatio-temporal dynamics of cotton plantation in Xinjiang for the period of 1949~2007. Also by using Fuzzy Theory and AHP method, an optimal interaction model between cotton plantation scale and the influencing factors in Xinjiang was constructed. Bused on the study, cotton acreage in Xinjiang had increased from 33.41×10³ hm² in 1949 to 1 782.60×10³ hm² in 2007. The increase in cotton acreage was mainly characterized by staging and volatility. Temporal dynamics in cotton acreage were different for the main cotton-cultivating areas in South Xinjiang, North Xinjiang and East Xinjiang. South Xinjiang presented the most obvious dynamics with dominant effect on cotton plantation in Xinjiang. Cotton-cultivating area in Xinjiang was divided into four groups according to oasis location. With different temporal dynamics among groups in cotton acreage, obvious dynamics were observed in Tarim River Basin and Northwest Border Oases. Based on the Fuzzy Theory and AHP analyses, the optimal scale of cotton industry in Xinjiang was 800×10³~1 000×10³ hm² per year. Cultivation scales of 600×10³~800×10³ hm² (second place), 400×10³~600×10³ hm² (third place) and >1 000×10³ hm² (last place) were less promising. This was sufficient evidence for choosing a rational scale for cotton production industry in Xinjiang.