The invention relates to a method for removing olefin from mixed aromatics. The method comprises the following steps: performing heat exchange on a mixed aromatic raw material, filling into a heat separator, controlling the temperature of the heat separator to be 100-300 DEG C and the pressure to be 0.02-0.2MPa, discharging a part of heavy components in the mixed aromatic raw material from the bottom of the heat separator, discharging other components from the upper part of the heat separator, feeding into a nonhydrorefining reactor, and contacting and reacting with a nonhydrorefining catalyst, thereby removing olefin from the mixed aromatic raw material. By adopting the method for removing olefin from mixed aromatics, a part of heavy components in a C<8+> mixed aromatic raw material can be effectively removed, and the operation period of the nonhydrorefining olefin removal catalyst can be remarkably prolonged.