The invention relates to a combined process for increasing yields of low-carbon arenes and low-carbon olefins by using pyrolytic C6<+>. The process comprises the following steps: carrying out selective hydrogenation on pyrolytic C6<+> in a hydrogen atmpsphere to remove diolefins, alkenyl arenes and other carbon deposit precursors, and carrying out alkyl arene pyrolysis and nonarene aromatization reaction on the liquid-phase product in a catalytic pyrolysis reactor to generate high-added-value low-carbon arenes and olefins; and after separating the products, carrying out polycyclic arene hydrogenation ring-opening reaction on the C9<+> heavy fraction to obtain alkyl arenes suitable for catalytic pyrolysis, and returning the monocyclic alkyl arenes to the catalytic pyrolysis reactor, thereby finally achieving the goal of producing more high-added-value BTX and low-carbon olefins. The combined process can be used for treating all-fraction pyrolytic C6<+>, solves the problem of incapability of reasonably utilizing pyrolytic C6<+>, and has higher pyrolytic C6<+> conversion rate, low-carbon olefin selectivity and BTX selectivity.