The present invention provides an oxyhydrogen preparation device capable of adjusting hydrogen content and a using method thereof. The device comprises a housing for accommodating an oxygen production device, a hydrogen production device, a control module (14), and a power supply module (19), wherein the power supply module (19) is configured to supply power to each said device; the oxygen production device is configured to separate oxygen from air and store the oxygen for backup supply; the hydrogen production device is configured to produce hydrogen or oxyhydrogen for backup supply based on the principle of water electrolysis; the control module (14) is configured to control and adjust the oxygen flow, detect the oxygen concentration, and adjust the flow of the oxyhydrogen and the hydrogen content to a preset range; and the oxygen produced by the oxygen production device converges with the hydrogen or the oxyhydrogen produced by the hydrogen production to a gas outlet (17) of the oxyhydrogen gas preparation device through a pipeline, and then discharged after humidification or discharged directly. Further disclosed is a using method of the device. The advantages such as long service life, adjustable hydrogen content, adjustable oxyhydrogen flow are achieved.