Disclosed is a method for directly synthesizing monocyclic aromatic compounds and long-chain olefin compounds from a carbon dioxide-rich synthetic gas and, specifically, a method for directly synthesizing monocyclic aromatic compounds and long-chain olefin compounds from a carbon dioxide-rich synthetic gas, the method comprising a step of preparing a C1-C15 short-chain hydrocarbon by Fischer-Tropsch (FT) synthesis and a step of preparing monocyclic aromatic compounds and long-chain olefin compounds by dehydrogenating the short-chain hydrocarbon products, and maximizing the yield of the short-chain hydrocarbon by using, as a synthetic gas to be used in FT synthesis, a carbon dioxide-rich synthetic gas in which the molar ratio of hydrogen, carbon monoxide and carbon dioxide is delimited to a specific range, and maximizing the yield of the monocyclic aromatic compounds or the long-chain olefin compounds by specifying the composition of a catalyst to be used in the dehydrogenation and the temperature and pressure condition.