The invention provides a method for preparing a volcanic stone adsorbent and a method for enriching catechin antioxidants, and the method for preparing the volcanic stone adsorbent includes the following steps: providing 24 mesh to 40 mesh volcano stone particles; using a citric acid aqueous solution for soaking the volcano stone particles for some time, washing and drying the volcano stone particles; and using an ethanol solution for soaking the dried volcano stone particles, washing and drying to obtain the granular volcano stone adsorbent. The method for preparing the volcanic stone adsorbent has the advantages that the adsorbent is made by use of the characteristics of being porous and hard in texture of natural volcanic stones without use of toxic and harmful chemical solvents, an adsorption column is not easy to block, and adsorption and elution efficiency are high.