A gas generator, comprising: a water tank, having a first hollow portion for containing electrolyzed water; and an electrolysis device, disposed inside the first hollow portion of the water tank for electrolyzing the electrolyzed water to generate a hydrogen-oxygen mixed gas; wherein the level of water for the electrolyzed water filled into the first hollow portion of the water tank and the electrolysis device can be higher than 90% of a full level of water of the water tank; the water tank further comprising a pipe for outputting the hydrogen-oxygen mixed gas, which pipe, when the electrolysis device pauses electrolyzing the electrolyzed water for generating the hydrogen-oxygen mixed gas, can be used to recharge the electrolyzed water for allowing the first hollow portion of the water tank and the electrolysis device to be filled with the electrolyzed water; the electrolysis device further comprising a partition and an electrolysis tank, the partition comprising a connecting hole, with the partition dividing the first hollow portion into an upper portion and a lower portion, the upper portion and the lower portion being connected through the connecting hole; the electrolysis device further comprising a plurality of electrodes and a pad, the plurality of electrodes being respectively disposed in the space inside the electrolysis tank for forming a plurality of electrode channels, and the pad being disposed on the upper surface of each electrode and having a plurality of upper vias, with the upper portion of the first hollow portion being connected with the plurality of electrode channels through the plurality of upper vias of the pad, and each electrode channel (S 1) being respectively connected with the upper portion of the first hollow portion through the corresponding upper via; with the electrolysis tank further having a lower surface, the lower surface of the electrolysis tank having a plurality of lower vias, the lower portion of the first hollow portion being connected with the plurality of electrode channels (S 1) through the plurality of lower vias of the lower surface of the electrolysis tank, and each electrode channel (S 1) being respectively connected with the lower portion of the first hollow portion through the corresponding lower via. a water tank, having a first hollow portion for containing electrolyzed water; and an electrolysis device, disposed inside the first hollow portion of the water tank for electrolyzing the electrolyzed water to generate a hydrogen-oxygen mixed gas; wherein the level of water for the electrolyzed water filled into the first hollow portion of the water tank and the electrolysis device can be higher than 90% of a full level of water of the water tank; the water tank further comprising a pipe for outputting the hydrogen-oxygen mixed gas, which pipe, when the electrolysis device pauses electrolyzing the electrolyzed water for generating the hydrogen-oxygen mixed gas, can be used to recharge the electrolyzed water for allowing the first hollow portion of the water tank and the electrolysis device to be filled with the electrolyzed water; the electrolysis device further comprising a partition and an electrolysis tank, the partition comprising a connecting hole, with the partition dividing the first hollow portion into an upper portion and a lower portion, the upper portion and the lower portion being connected through the connecting hole; the electrolysis device further comprising a plurality of electrodes and a pad, the plurality of electrodes being respectively disposed in the space inside the electrolysis tank for forming a plurality of electrode channels, and the pad being disposed on the upper surface of each electrode and having a plurality of upper vias, with the upper portion of the first hollow portion being connected with the plurality of electrode channels through the plurality of upper vias of the pad, and each electrode channel (S 1) being respectively connected with the upper portion of the first hollow portion through the corresponding upper via; with the electrolysis tank further having a lower surface, the lower surface of the electrolysis tank having a plurality of lower vias, the lower portion of the first hollow portion being connected with the plurality of electrode channels (S 1) through the plurality of lower vias of the lower surface of the electrolysis tank, and each electrode channel (S 1) being respectively connected with the lower portion of the first hollow portion through the corresponding lower via.