The invention provides a hydrogen-oxygen generating apparatus, comprising: a tube member; an insulated tube inserted inside the tube member; an electrode plate member which is inserted inside the insulated tube and composed of first and second electrode plates, a plurality of annular separating members and first and second electrode bars, wherein, a first big hole and a first small hole are respectively formed above and below a central hole of the first electrode plate, a second small hole and a second big hole are respectively formed above and below the central hole of the second electrode plate, the annular separating members are installed between first and second electrode plates, the first electrode bar is inserted into the first small hole and the second electrode bar is inserted into the second small hole after first and second electrode plates are ranged, the first big hole is aligned with the second small hole and the first small hole is aligned with the second big hole; a front cover and a back cover respectively having first and second via holes and third and fourth via holes; an insulated pad connected on first, second, third and fourth via holes, wherein first and second electrode bars are inserted into first, second, third and fourth via holes and the insulated pad.