The present invention provides a method for preparing organometallic composite material, comprising: providing PVC resin, activated calcium carbonate, plant fiber, calcium stearate, barium sulfate, paraffin, sodium bicarbonate, zinc laurate, nanometre titanium dioxide, organometallic salt, shell powder, carbon nanotube, talcum powder and stabilizer; mixing and heating; subject to first cooling after extrusion and second cooling under vacuum; towing to obtain the organometallic composite material, wherein the organometallic salt is a benzoic acid metal salt mixture. The present method can significantly reduce the processing temperature of PVC composite by 20 to 50° C., and also increase the toughness and strength of the material so as to alleviate the exudation of the composite material as in the conventional technologies and extend the lifespan of the composite material.