In the upstream Lake Taihu Basin, economic development affects the discharge amount of wastewater and influent total phosphorus (TP) load. In order to reveal the trend of water environment quality with economy in the Lake Taihu Basin, we simulated the relationships between wastewater discharge, influent TP load and Gross Domestic Product (GDP) per capita for the upstream Lake Taihu Basin (1978-2012) using Environmental Kuznets Curve (EKC) models. The results showed that the average annual growth rate of GDP per capita was 10.3%-11.8% based on 1978 prices in the upstream Lake Taihu Basin. Meanwhile, during 1990-2012, the annual mean discharge amount of industrial wastewater and the annual mean total discharge amount of wastewater were 647.99 million tons and 937.07 million tons, respectively. The export of EKC models revealed that both of industrial wastewater and total wastewater discharge had inverted-U-shaped relationships with GDP per capita, and decreased during 2006- 2007 and 2008-2009, respectively. Moreover, influent TP load was positively related with the total wastewater discharge in the upstream of Lake Taihu Basin, presenting an inverted-U-shaped relationship with GDP per capita and declining during 2007-2008. During 1978-2012, the influent TP load ranged from 850 t/a to 1200 t/a before 1990s; increased to 1300-2000 t/a after 1990s. The EKC models provided scientific evidence for estimating wastewater discharge and the influent TP load as well as their changeable trends for the upstream Lake Taihu Basin from an economic perspective.