In this study. ferric chloride coagulation and gamma-ray irradiation(50 kGy) were used to treat livestock wastewater. As the ferric chloride coagulant dosage was increased to treat livestock wastewater, the removal efficiencies of SCODcr, T-N and T-P increased. When the maximum dosage of ferric chloride coagulant(0.244 mmol) was applied to livestock wastewater, the removal efficiencies of SCODcr, T-N and T-P were 56.9, 18.5 and 92.0%, respectively. In case of gamma-ray irradiation(50kGy) after applying 0.244 mmol ferric chloride coagulant to samples, the removal efficiencies of SCODcr, T-N and T-P were 78.4, 19.9 and 99.7%, respectively. From the results of this study, gamma -ray irradiation after coagulation to livestock wastewater improved treatment efficiency.