The invention discloses a flat plate type dialysis device, a production method thereof and a dialyzer produced thereby. The dialysis device comprises a plurality of flat plate type dialysis units which are connected between a liquid inlet main pipe and a liquid outlet main pipe in parallel. The production method comprises the following steps: production of separation plates, production of the flat plate type dialysis units, and production of the flat plate type dialysis device by connecting the plurality of flat plate type dialysis units with the liquid inlet main pipe and the liquid outlet main pipe after integral connection. The dialyzer comprises a tank body, and one or more than two sets of flat plate type dialysis devices arranged in the tank body, wherein an air floating device and a stirring device are arranged in the tank body. The flat plate type dialysis device has the advantages of simple structure, good sealing effect and convenience for cleaning and maintenance. The production method has a simple technique flow, and needs no complex equipment for processing. And the dialyzer has the advantages of convenience for mounting, dismounting, cleaning and maintenance, difficulty in blockage, and good adaptability to liquid which has high solid content and high concentration.