First, based on the classical method of economic base analysis, this paper studies the change of Tianjin industry comparative advantage from 1990 to 1995 by comparing with Beijing and Shanghai. The major conclusion is that electronic and telecommunications, transportation equipment manufacturing, food production of Tianjin are becoming to take precedence, while chemical fibers and raw chemical materials and chemical products with good natural environment declining. Then the paper concentrates on industrial structure and leads to a viewpoint that Tianjin industry exerts lower environmental pressure and knowledge and technology intensive industry sectors with lower input of water and less pollution tend to burgeon. Moreover, the author gives some advice on developing a proper industry relationship between Beijing and Tianjin.