In this study, potassium permanganate pre-oxidation / powdered activated carbon adsorption / flotation / ultrafiltration combined process was used for treating micro-polluted source water. The experimental results show that treated by potassium permanganate pre-oxidation / powdered activated carbon adsorption / flotation the removal rate on the turbidity, algae, CODMn and UV254 were 91.7%, 90.6%, 45.9% and 19.2% respectively. The removal rate of ultrafiltration unit on the turbidity, algae, CODMn and UV254 were 98.8%, 84.9%, 22.4%, 3.1% respectively. The NH3-N removal efficiency is not obvious. The water quality treated by the combined process can reach "sanitary standard for drinking water" (GB5749-2006) stably, and such a combined process can be recommended as the process for upgrading the existing water plant.