Abstract: This paper sets up an input-output theoretical model for evaluation of mass sports by reference of others' achievements. This model depends on Delphi method,factor analysis method and principal component analysis to establish an evaluation index system of mass sports in Western China. This evaluation index system includes the four main influencing factors of living quality of,resources guarantee,benefits and effects of mass sports and social environment and 13 concrete targets. The paper also makes a comparison and ranking of mass sports between Sichuan,Chongqing and Yunnan through new evaluation index system.