Co-removal of oscillatoria algae and its potential odorous metabolite dimethyl trisulfide (DMTS) in simulated algae-laden alkaline source water by potassium ferrate (K2FeO4) was investigated in contrast to potassium permanganate (KMnO4) pre-oxidation followed by polyferric chloride (PFC) under varying conditions, including pH, initial oxidant dosage and turbidity. Based on the pre-comparison with PFC, the optimal dosage of PFC in the combined KMnO4 pre-oxidation-PFC treatment was determined. Potassium ferrate resulted in 92.4% removal of algae, higher than PFC when the dosage was equivalent as measured by Fe and KMnO4 showed obviously positive effect as a coagulation aid. Degradation of dimethyl trisufide (92.5%) by potassium ferrate was better than the pre-oxidation of potassium permanganate (74.6%), and the treatment time was decreased from 10 min to 1 min.