The utility model relates to a plugging cap of a leading-down steel pipe of power optical cables, and effectively solves the problem that the optical cables in the leading-down steel pipe cannot be pulled when the optical cables need to be pulled out of the steel pipe for replacement, wiring and laying due to the fact that the steel pipe is plugged by fireproof mud or fireproof mud falls into the steel pipe. The plugging cap comprises a sleeve cap and a screwing cap, wherein the sleeve cap is cylindrical and hollow, the outer wall of the upper end of the sleeve cap is provided with outside threads, the outer side surface of the sleeve cap is provided with a vertical crack which is communicated with the inner side wall, and the inner wall of the sleeve cap is pasted with a layer of first soft rubber waterproof blockage material; and the screwing cap is also cylindrical and hollow, the lower end of the screwing cap is provided with inside threads, the upper end of the screwing cap includes a hexagonal bolt head, the diameter of the bolt head is lower than that of the screwing cap, and the upper end of the inside threads of the screwing cap is pasted with a layer of second soft rubber waterproof blockage material. The plugging cap is ingenious in structure and low in investment, can be used to pull optical cables easily, and improves the working efficiency of workers.