The invention provides a membrane separation method applicable to desalting and recycling of sewage. The method is applicable to low-concentration salt-containing sewage (wastewater). The sewage desalting method provided by the invention is realized by filtration and adsorption effects of a conductive composite membrane. The conductive composite membrane is operated in an immersed manner by adopting a flat plate membrane assembly. Under an electrified condition, the conductive composite membrane finishes adsorption and recovery of ionic type pollutants. Due to the membrane separation and electrical adsorption coupled desalting process provided by the invention, the service life of an adsorption material is prolonged by intercepting particular pollutants in advance, the adsorption effect is improved and the energy consumption is reduced. The composite membrane separation method provided by the invention is compact in device, and convenient in operating management; a removal effect of ions is controlled by controlling an externally applied voltage and membrane flux, and purification and removal of pollutants in sewage (wastewater) are realized under the condition of appropriate voltage and membrane flux.