Waste activated sludge (WAS) conditioning is crucial for enhancing sludge dewaterability and effectively reducing the management cost. The feasibility of bio-enzymes with Fe2+-activated advanced oxidation processes (AOPs) for WAS conditioning was investigated in this study. Two representative bio-enzymes, α-amylase and neutral protease, and two typical AOPs, the Fenton system and Fe2+/Ca(ClO)2 system, were chosen. The medical dosages of AOPs were first optimized by single-factor experiments. On this basis, the dosages of bio-enzyme, ferrous ion, and oxidant were optimized using the response surface method (RSM). Results showed that neutral protease combined with the Fe2+/Ca(ClO)2 system performed better in CST and SRF reduction rates while reducing the medical dosages of AOPs. Under the optimal conditions of neutral protease dosage of 20.9 mg/g TSS, Fe2+ dosage of 0.64 mmol/g TSS, and Ca(ClO)2 dosage of 0.54 mmol/g TSS, the reduction in sludge CST and SRF reached 84.81 % and 94.06 %, respectively. The neutral protease with the Fe2+/Ca(ClO)2 system was a potential method for improving sludge dewatering performance.