The invention provides a vapor cracking catalyst, an application of the vapor cracking catalyst, and a preparation method of the vapor cracking catalyst. In addition, the invention also provides a direct combustion method of a hydrogen gas obtained by vapor cracking. A plenty of cheap raw materials are adopted to prepare the catalyst provided by the invention and it leads to lower cost for production. In addition, the catalyst provided by the invention is capable of controlling the vapor cracking speed steadily so that the hydrogen gas is produced steadily and occurrence of explosion accidents is avoided effectively. The direct combustion method of a hydrogen gas obtained by vapor cracking provided by the invention truly achieves for the first time the fancy of producing hydrogen energy by water.