Taking provinces as study cases, 15 comprehensive factors, involving natural geography, agricultural production, economic and social information, were formulated to evaluate the agricultural environment in western China by factor analysis method. The results showed that comprehensive scores were distinct among different cases. The score of Sichuan was the highest, that of Chongqing second and that of Guangxi the third. Qinghai got the lowest score, ranking the twelfth. The general environment quality was better in moist southern regions than that in frigid northern regions in the provinces of western China. Therefore, the appropriate eco-environmental construction measures at provincial level should be proposed to increase vegetation coverage, control water and soil loss, and prevent desertification and wind erosion. To develop eco-agriculture is an inevitable selection for environment construction and improvement in western China.