The invention discloses a preparation method and application of modified calcium carbonate for high-filling wet-strength paper. The preparation method comprises the following steps of: dispersing precipitated calcium carbonate in water, controlling the mass concentration between 20% and 50%, stirring, and then adding polyamide polyamine epichlorohydrin of the mass concentration of 0.2 to 2% obtained by being diluted with water, wherein the amount of the polyamide polyamine epichlorohydrin is 1 to 25% of the dry mass of the precipitated calcium carbonate; and stirring for 30 to 120 minutes at 150 to 500r / min, adding a low molecular weight cationic polyacrylamide enhancer with a molecular weight of 0.8 to 2 million, and stirring to obtain a modified calcium carbonate filler. The filler is used for producing the high-filling wet-strength paper, thereby obtaining better retention, dry strength, wet strength, and sizing degree. According to the preparation method and the application, the process is simple, the application is convenient, the problems that the high-filling wet-strength paper has poorer dry and wet strength, low filler retention and sizing impediment can be better solved, and the cost of production enterprises is reduced.