The rapid growth of high-tech industry in Taiwan has brought serious environmental problems and concern by the Government, especially in semiconductor and photovoltaic (PV) manufacturing. On Dec. 15, 2010, Taiwan Environmental Protection Agency (EPA) announced new wastewater discharge standard for PV manufacturing, including Total Toxicity Organics (TTO, 1.37 mg/L), indium (In, 0.1 mg/L), gallium (Ga, 0.1 mg/L), molybdenum (Mo, 0.6 mg/L) and Acute Toxic Unit (TUa, 1.43). In this study, Daphnia magna immobility test was employed to detect toxicity of wastewater and effluent of semiconductor manufacturing process. TUa is higher than 5 for CMP-mixed HF wastewater, acid-alkali wastewater and effluent against D. magna. Toxicity risk of all wastewater flows mentioned above is ‘’very toxic’’.