The invention discloses a method of modifying phenol substances through a CO2 biological conversion method. The method comprises the steps of: by means of gene-engineering bacteria, combining CO2 onto an aromatic ring of a phenol substance to obtain hydroxybenzoic acid and a derivative; and reducing the carboxyl group, which is generated after carboxylation of the phenol substance, thereby generating corresponding aldehydes or alcohols. The method not only completely reduces carbon emission, but also technically avoid introduction of solid or liquid impurities due to addition of other carbon sources, so that the method reduces synthesis steps, reduces work load of separation and is more economical.