The invention discloses a catalyst, a preparation method for the catalyst for producing a carbon nanotube by using medical stone as a carrier and an application and relates to the field of materials science. The preparation method comprises the following steps: (1) distributing the catalytic elements of a carbon nanotube in a nanometer mode on the surface of the medical stone, thereby acquiring acatalyst precursor and (2) performing high-temperature calcination, crushing, sizing screening and packaging on the catalyst precursor acquired in the step (1), thereby acquiring the catalyst for producing the carbon nanotube. The specific surface area of the acquired catalyst is 10-1000m2/g. According to the method, the raw materials are low in cost, the process is simple, the granular shape of the catalyst is controllable, the catalytic elements are uniformly distributed and the method is green and environment-friendly.