Abstract: The fuzzy mathematical method was used to evaluate the water quality of the Taizi River. Eight main stream sections such as Laoguanlazi, Xingan, Senwobaxia, and six branch stream sections such as Tanghe Bridge, Hehong Bridge, Mengliu, were investigated with seven evaluation factors such as BOD₅, COD, NH₃-N, volatile phenol. An evaluation factor matrix was established and the comprehensive water quality of each section was obtained by fuzzy computing with a weighting calculation. Analysis results revealed that the water quality in the monitoring sections of the main and branch streams of the Taizi River was very poor since 85.7% of the total monitoring sections were Grade V water. The factors of COD and NH₃-N were the main pollutants, followed by the BOD₅ and volatile phenol, which should be controlled preferentially in the Twelfth Five-Year Plan for Taizi River recovery.