The invention discloses filter paper added with sulfur-loaded coconut-shell activated carbon and used for an automobile filter, and a preparation method thereof. According to the invention, waste coconut shell is used as a raw material and undergoes impregnation modification by an aqueous sodium sulfide solution and carbonization with the novel heat energy technology microwave heating so as to prepare coconut-shell activated carbon, and the prepared activated carbon and sulfur are subjected to microwave activation and modification; thus, on the one hand, elemental sulfur can be loaded on the surface of the activated carbon, and on the other hand, the surface of the activated carbon becomes rough and is of a concave-convex shape after microwave heating and pores in the activated carbon become narrow slits and inwardly extend, which facilitates adsorption of granules, especially mercury, in automobile tail gas. The filter paper prepared by compounding the sulfur-loaded coconut-shell activated carbon, used as a filling material, and chlorinated polyvinyl chloride fibers and wood pulp fibers has high porosity, strong absorptivity, excellent high-temperature resistance and low moisture-absorbing deformability; and a filter element prepared from the filter paper provided by the invention has good stiffness, is easy to mold and has physical strength and properties like abrasion resistance, bending resistance and tensile resistance, and the network pores of the filter element are difficult to collapse.