The utility model relates to a cassette water-electrolytic oxygen and hydrogen generator which is composed of more than two electrolytic units, wherein each electrolytic unit forms a cassette shape, and is composed of a current conducting cassette body, electrode plates, an insulated bracket, an insulated pad and a cover plate. The insulated bracket is positioned in the current conducting cassette. At least two electrode plates are arranged on the insulated bracket with distance. The sides of the two electrode plates and the distance between the electrode plates form an electrolytic slot. The insulated pad is positioned between the current conducting cassette body and the cover plate. The current conducting cassette body, the insulated pad and the cover plate are combined integrally by fasteners. Because the sealing surface of the cassette water-electrolytic oxygen and hydrogen generator is reduced and the wall of the electrolytic slot is made of metal material, the sealing property and the operational reliability are effectively improved. Simultaneously, the cassette water-electrolytic oxygen and hydrogen generator has the advantages of simple structure, convenient repair, good heat dissipation performance, etc.