The invention belongs to an energy-saving type wet-process desulfurization device and a process method. The energy-saving type wet-process desulfurization device comprises a lean liquid groove, wherein the lean liquid groove is respectively connected with an energy recovering unit and an energy supplementing unit by a first three-way joint; the energy recovering unit and the energy supplementing unit are respectively connected with a liquid inlet pipeline in at least one desulfurization tower device; a liquid outlet at the bottom of the desulfurization tower is connected with a first adjusting valve, a turbine, a second adjusting valve and a flashing evaporation groove in sequence by pipelines; the energy recovering unit comprises a first gate valve connected with a second end of the first three-way joint; the first gate valve is connected with a third adjusting valve by a lean liquid pump in the energy recovering unit; and the lean liquid pump in the energy recovering unit is connected with a power output end of the turbine by a seat type clutch. The energy-saving type wet-process desulfurization device and the process method have the advantages that the equipment structure is simple, the process flow design is reasonable, the investment is less and the efficiency is high.