The invention relates to a preparation method of rich mineral paper and belongs to the technical field of rich mineral papermaking. The method adopts polyacrylic acid and poly (4-methyl-1-pentene) aspolymer raw materials, by utilizing the poly (4-methyl-1-pentene), the density of the rich mineral paper can be improved, the weight is reduced, meanwhile, the transparency of the rich mineral paper can be improved, activity groups between the polymer raw materials is improved, the hardness of the rich mineral paper is reduced, then phosphoric acid is used for soaking, the modification of a subsequent substance to the polymer raw materials is improved, the polymer raw materials are modified by maleic anhydride, and a pore-forming agent is finally added for pore forming, so that a formed membrane is a membrane with pores, substances in carbide slag are extracted to obtain a mixed solution containing calcium chloride as a main substance, trace elements are carried, then the porous membrane is soaked in an impregnation liquid, the pores are filled by adsorption of calcium carbonate crystals, the adding amount of medium ore powder in the prior art is reduced, and the density of the rich mineral paper is reduced, and meanwhile, the stiffness of the rich mineral paper is improved.