NOVELTY - Microalgal breeding livestock-poultry waste water purifying device comprises a biogas liquid tank, a liquid mixing tank, an algal photobioreactor, a liquid storage tank, flocculating algal liquid collecting tank, and clean water tank. The biogas liquid tank through marsh liquid pipe is connected with the liquid mixing tank. The photobioreactor comprises a machine frame provided with multiple longitudinally stacked flat-type reactor. The bottom upper-lower layer flat plate reactor is provided with an effluent overflow pipe to allow liquid from upper to the lower plate reactor.    USE - Used as a microalgal breeding livestock-poultry waste water purifying device.    ADVANTAGE - The device cultures microalgae subsequently with waste water modulation, which greatly reduces the microalgal culture production cost; generates waste liquid containing nitrogen and phosphorus, which is used as nutrient substance for culturing microalgae; reduces each index in the waste water; and improves water quality after purifying waste water.    DETAILED DESCRIPTION - Microalgal breeding livestock-poultry waste water purifying device comprises a biogas liquid tank, a liquid mixing tank, an algal photobioreactor, a liquid storage tank, flocculating algal liquid collecting tank, and clean water tank. The biogas liquid tank through marsh liquid pipe is connected with the liquid mixing tank. The photobioreactor comprises a machine frame, which is provided with multiple longitudinally stacked flat-type reactor. The bottom upper-lower layer flat plate reactor is provided with effluent overflow pipe to allow liquid from the upper plate reactor to the lower plate reactor. The bottom flat plate reactor overflow pipe is connected with the liquid storage tank. The liquid storage tank is further provided with the return pipe leading to upper layer flat-plate reactor. The upper return pipe is provided with a return liquid pump. The liquid mixing tank is provided with the upper layer plate and is connected with the reactor infusion tube. Each layer of flat-plate reactor is provided with a collecting tank liquid outlet pipe. The upper liquid outlet pipe is provided with a liquid outlet switch. The collecting tank through connecting pipe and is connected with the clean water tank. An INDEPENDENT CLAIM is also included for purifying microalgal livestock-poultry breeding waste water, using microalgal livestock-poultry breeding waste water purifying device comprising (i) inoculating microalgae into the conical bottle filled with culture solution, placing in the shaking table to culture until the optical density (OD) of algal solution in the conical bottle is 0.6-0.7 time at OD680, carrying out seed expanding culture, (ii) transferring the liquid after expansion into the slurry mixing tank equipped with biogas slurry, continuously culturing the algae liquid reach 1.2-1.3 at OD680, (iii) starting the infusion pump, transferring the step (ii) obtained algae into photobioreactor and culturing, and purifying the algae solution via circulation return pipe and return liquid pump, and (iv) opening the outlet switch when the photobioreactor OD 680 reaches more than 3, flowing algal liquid in to the collecting tank, and closing the liquid outlet switch when the OD 680 reduced to 1.2-1.3.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic representation of the microalgal breeding livestock-poultry waste water purifying device.