The adsorption and transport properties of lithium ions (Li+) in covalent organic framework (COF)/graphene (G) composites (COF@G) were investigated using molecular simulations. The adsorption sites and sequence of Li+ were defined, and the corresponding adsorption energy was determined together with the apparent change in the morphology of COF@G. Additionally, the internal π-π stacking interactions and COF-G and Li+-G distances were calculated. When the saturated adsorption state was attained, the volumetric change rate of COF@G was lower than 25%, and the average voltage remained above 3.20 V. Under the same conditions, Li+ exhibited the highest conductivity on the outer surface of G. These results provide a theoretical basis for the practical applications of these systems.