Abstract: GGE biplot analysis method was adopted to explore and investigate the possible megaenvironments in the target cotton planting region with the trial locations including Anqing, Nanyang, Huanggang, Jingzhou, Wuhan, Xiangyang, Changde, Yueyang, Nanjing, Nantong, Jiujiang, Jianyang, Shehong and Cixi as the representatives for cotton fiber length selection in 27 independent sets of cotton variety trials in the Yangtze River Valley during the 2000~2010 periods, in order to provide the scientific basis for the decision-making of cotton variety selection and recommendation for the Yangtze River Valley. The Information Ratio(IR) adjustment method was implemented as a validate tool to ensure sufficient and necessary main principal component scores were selected in GGE biplot analysis. The conclusions showed that the cotton planting regions in Yangtze River Valley was divided into three distinct fiber length selection megaenvironments, namely,the first megaenvironment contains seven test environments including Anqin, Jiujiang, Wuhan, Nantong, Huanggang, Changde and Yueyang; the second megaenvironment contains four test environments including Jingzhou, Yancheng, Nanjing and Shehong; and the third megaenvironment contains test environment of Cixi, Jianyang, Xiangfan and Nanyang.