The invention discloses a composite flocculant for treating printing and dyeing wastewater. The composite flocculant for treating the printing and dyeing wastewater is prepared from the following rawmaterials in parts by weight: 15-25 parts of activated carbon fibers, 4-11 parts of acrylamide, 2-9 parts of sodium carboxymethyl cellulose, 5-17 parts of polyvinyl alcohol, 3-6 parts of a crosslinking agent, 0.003-0.006 part of an initiator, 3-5 parts of a polyethyleneimine-cellulose composite material, 10-15 parts of starch xanthate and 25-36 parts of modified bentonite. The composite flocculantprovided by the invention does not contain components which are complicated, have radiation and easily cause secondary pollution, all the used raw materials are natural, environment-friendly, low inprice and easy to obtain, the preparation method is simple, the feeding amount is small, the composite flocculant has multiple effects of flocculation sedimentation, adsorption decolorization, deodorization and the like, the sedimentation rate is high, the removal rates of organic matters, dye molecules and heavy metals are high, the structure and properties are stable, and the application range is wide.