A novel water treatment method for boiler feedwater of the invention comprises the following steps: sterilization, that is adding liquid chlorine, sodium hypochlorite or stabilized chlorine dioxide into a raw water tank, controlling the residual chlorine amount in water to be 0.2-0.5 mg/L; filtration, that is adding a polyaluminium chloride coagulant before a multimedium filter with an amount of 10-20 mg/L, controlling the water turbidity of the ultrafiltration feedwater to be not more than 0.1 NTU and the SDI to be not more than 3; adding a reducing agent of sodium bisulfite before ultrafiltration with an adding amount of 3-5 mg/L; reverse osmosis, that is performing desalination treatment by a reverse osmosis membrane device, continuously adding a PTP-0100 scale inhibitor before a security filter with an adding amount of 3-5 mg/L; continuously adding a Micro Treat BIO bactericide with an adding amount of 3-5 mg/L; additionally adding cleaning agents of Dimamite and High Flux once a month with an amount of 3-5% of the water amount to be produced; desalination, that is performing desalination by an electrical desalination system (EDI); deoxygenation, that is performing deoxygenation by a vacuum deoxygenator, adding 10-20 microgram/L of deoxidants, controlling the agent residual amount to be 5-20 microgram/L, adding a corrosion-inhibiting pH regulator to control the pH value to be 8.8-9.3.