The environmental distribution and migration of bisphenol A (BPA) has attracted attention due to its widespread use. The Erhai Lake Basin is dominated by agricultural production and tourism, and almost no industry. In this research, BPA pollution in the non-industrial region was investigated. BPA was found in all samples of inflow rivers, with concentrations ranging 2.80 ng/L~61.85 ng/L. The measured 15 rivers that account for 78.7% of the total inflow volume were inputting BPA concentration of 20.69 ng/L into Erhai Lake with an annual load of 8.54 kg/year. The measured BPA removal efficiency of sewage treatment plants ranged 49.8%~92.8%. Oxidation Ditch and A²O-MBR treatment process achieved the better BPA removal efficiency. The amount of BPA discharged directly to Erhai Lake from the effluent of the sewage plants each year was 1.63 kg. Based on the above research, a multimedia model of QWASI was established, and water concentration calculated was 0.203ng/L. A PNEC value considering more sensitive receptors was applied to this study, and it was indicated that there was a certain ecological risk in the water of the Boluo River estuary, while other rivers and lake were relatively safe. It was revealed that the ecological risk of BPA was relatively low in the Erhai Lake.