Abstract: To identify cotton fiber quality development process and indexes interactions in Liaohe Basin, we took the main planted cotton cultivar‘Liaomian 19’and earlier introduced insect resistant cotton cultivar ‘AC-33B’as test materials, labeled flowers in blooming day, conducted continuous sampling on the 9th, 15th, 21st, 27th, 33rd, 39th, 45th, 51st (6 days interval) day after blooming. The main fiber quality indexes were detected, such as fiber length, strength, micronair, elongation and uniformity. The developing condition and correlation coefficient of each index were compared, and then simulation models were formed. Except that micronaire values were more sensitive to environmental factors, the development process of the rest indexes presented a “S”curve, and two cultivars had similar trends. But the interaction methods between each index of the 2 cultivars were different. At the same time, the development of every index was highly consistent and relevant; the fiber elongation development was the dominant. Cotton fiber should stay in plant more then 40 days, but over-maturing was not conducive to obtaining high quality cotton fiber.