The invention discloses a high-frequency fatigue superheat testing device of an oxyhydrogen steam environment. The high-frequency fatigue superheat testing device comprises an oxyhydrogen steam generating device, wherein the oxyhydrogen steam generating device comprises a steam generator and a flow control device, the steam generator is communicated with the gas inlet pipe of an environment testing device through a first pipeline, and the flow control device is connected with a hydrogen and oxygen supply pipeline, arranged on the first pipeline and used for controlling the content of hydrogen and oxygen dissolved in steam. The high-frequency fatigue superheat testing device has the advantages that the content of the hydrogen and oxygen dissolved in the steam in the first pipeline is controlled by regulating the feeding flow of hydrogen and/or oxygen through the flow control device, the content of the hydrogen and oxygen of the steam feeding into the environment testing device can be controlled, and quantitative analysis of coupling data under the oxyhydrogen steam environment is achieved.