The invention discloses a method for producing paraxylene by coal-based mixed aromatics and a method and a device for producing paraxylene by using naphtha of direct coal liquefaction. The method for producing paraxylene by the coal-based mixed aromatics comprises the following steps of: (1) carrying out fractional distillation on materials containing coal-based mixed aromatics under the condition of fractional distillation; (2) carrying out alkylation reaction on benzene obtained by fractional distillation and returning products back to step (1); (3) carrying out disproportionation and transalkylation reaction on methylbenzene obtained by fractional distillation and C9-C12 aromatics, and returning products back to step (1); (4) separating C8 aromatic obtained by fractional distillation under the conditions of adsorption and separation to obtain the paraxylene and a third product. The method disclosed by the invention has the advantage that the resources of the coal-based mixed aromatics can be fully utilized to produce the paraxylene.