The invention belongs to the technical field of activated carbon, and particularly relates to a high-hardness activated carbon, and a preparation method and application thereof. The ball disk hardnessof the high-hardness activated carbon is larger than or equal to 95%. When the preparation method of the invention is used, for example, phosphoric acid is added into an activation process, the high-hardness activated carbon can be prepared by a good yield and a mild reaction condition. Due to high hardness, in a use process, ash content is small. In addition, the activated carbon has excellent adsorption characteristics, can be used for adsorbing gold, and also can efficiently adsorb harmful gases, such as one or multiple of CO, H2S, HCl, SO2, NOX, formaldehyde, aromatic hydrocarbon gas, ammonia and the like. The high-hardness activated carbon can be used for preparing chemical protective clothing materials.