The invention discloses an advanced treatment method for desulphurization wastewater of a power plant. The advanced treatment method is mainly composed of ultrafiltration reverse osmosis treatment, evaporative concentration treatment and treatment with a dry slag system and is characterized by comprising the following steps: injecting the desulphurization wastewater of the power plant into an intermediate water tank after conventional treatment; conveying wastewater having a high chloride ion concentration in the intermediate water tank into a reverse osmosis apparatus for concentration and conveying formed concentrated water with high salt content into an evaporation plant; further concentrating the concentrated water in the evaporation plant; injecting a small amount of high-concentration water obtained after two concentration operations into the boiler dry slag system for humidifying of dry slag; and conveying pure water filtered out from the reverse osmosis apparatus and condensed water obtained by evaporation of the evaporation plant to a clear water for recycling. According to the invention, desulphurization wastewater of the power plant is concentrated twice after conventional treatment so as to form undischargable high-salt-content water for recycling in the power plant, so advanced treatment of desulphurization wastewater of the power plant is realized; and the method is an ideal desulphurization wastewater treatment scheme and has high promotion value.