The invention discloses an environment-friendly smoke abatement and dust removal boiler flue system. The environment-friendly smoke abatement and dust removal boiler flue system comprises a boiler, awater membrane dust remover, a circulating water tank and an ash melting tank, wherein a PH value measurer is arranged in the circulating water tank, and a floating device is installed on the PH valuemeasurer; and the floating device comprises a floating seat and a fixing device, wherein the floating seat is in a circular ring shape, the center of the floating seat is vertically and fixedly connected with the PH value measurer, and a fixing device is fixedly connected to the outer peripheral ring of the floating seat; and the fixing device comprises three supporting rods which are located onthe same horizontal plane, and the supporting rods are clamped in three grooves in the inner wall of the circulating water tank. According to the method, the PH value monitoring of the circulating water tank and the alkaline substance putting link of the ash melting tank are well linked, and meanwhile, the phenomena of alkaline matter waste and inlet blockage are prevented, dust removal and desulfurization of flue gas of a boiler can be effectively realized, and pollution to the atmospheric environment can be weakened.