The invention relates to a preparation method of a carbon-based adsorption material and belongs to the field of water treatment materials, in particular relates to a method of preparing the carbon-based adsorption material by means of an anodizing method. The adsorption material provided by the invention is prepared by the following steps: oxidizing and peeling a fine graphite board in deionized water by means of an electrochemical method to form a stable oxidized nano carbon solution; and then drying and grinding the solution to prepare the material. Detection results verify that the adsorption material prepared by the method has good adsorption performance to heavy metal ions, the adsorption performance being superior to that of a common adsorption material activated carbon. The electrochemical preparation method is low in cost and green and environment-friendly. Raw materials are only the graphite board and deionized water, and intermediate products and products are non-toxic and pollution-free.