Based on the analysis of the variation of the grain production during 1949-2003 in Huanxian, factors affecting the grain production were explored by using the method of principal component analysis. Results showed that development of society and economy, improvement of agricultural technology and natural disasters were three primary factors influencing grain production. Based on these factors, a GM(1,1) model was established and used to predict their trends in 2010, 2015 and 2020, which are expected to serve as scientific basis for accelerating agricultural modernization and developing sustainable agriculture in Huanxian County.