The invention provides a method for preparing a multilevel porous carbon base composite phase change material, and belongs to the field of composite phase change materials. The method comprises the following steps: at first, preparing an organic metal skeleton material by using such methods as a solution method, a solvothermal method or a stirring synthesis method; with the organic metal skeleton material as a template, high temperature carbonizing under the protection of an inert gas, and changing the carbonizing temperature and the post treatment manner to obtain a multilevel porous carbon material with a super-large specific surface area and a super-large pore volume; selecting proper solvents according to different kinds of phase change core materials, preparing the phase change core materials to a solution, dispersing the porous carbon material into the solution, removing the solvent by such manners as heating, and meanwhile the phase change core materials are adsorbed and limited in the porous carbon material. The composite phase change material prepared by the method provided by the invention has good thermal storage property, can effectively avoid the leakage problem of the phase change core material, and has the advantages of excellent heat transfer property, good cycling stability and wide application range, and the process is simple and is suitable for large-scale production.