The paper introduces the experimental study on combined treatment of alkaline dyeprinting wastewater and FGD of medium or small sized boilers.The original wet precipitator of the boiler can be used.Not only the result of dust-removing, but also the desulfurization of flue gas and wastewater treatment can be guaranteed.The experiments show that the desulfurizing efficiency was good.The pretreated wastewater may be treated by iron filings-flying ash and activated sludge process.Then the indexes will meet the national discharge standards.Thus excellent environmental and economic benefit may be obtained.