Incremental tendency method is used to discriminate master factors of regional environmental quality. In this article, incremental tendency method has been revised. Taken Tianjin sea area as an example, the collation of environmental quality master factors in 2006 has been listed. It is advanced that environmental quality master factors of Tianjin sea area are mainly inorganic nitrogen and petroleum substances, and pollution management should also be aimed at these types of substances. Finally the meaning of new model in application has been explained. It provided practical basis for sustainable development of Tianjin sea area.