Carbon dioxide, CO₂ fixation is a potential technology for the CO₂ reduction and synthesis of organic compounds from CO₂ as a starting material in environmental science and technology.  In this review, the photochemical and enzymatic CO₂ fixations based on the conversion to organic molecule or reduction of CO₂, with the combination of photoredox system consisting of an electron donor, a photosensitizer and an electron carrier, and various dehydrogenases with the function of CO₂ fixation in aqueous media are introduced.