The utility model relates to the field of electric power system safety protection, in particular to a portable cable connector plugging insulation rubber cap. Wherein the upper end of the insulating cylinder body is sealed, the lower end of the insulating cylinder body is open, the lower end of the insulating cylinder body is connected with a flared cable fixing insulating wall sleeve, the outer surface of the wall sleeve is provided with threads, the cylinder body is sleeved with a fastening nut screwed with the threads, and an elastic damping insulating baffle is arranged at the upper end inthe cylinder body. A double-fixing mode of fastening an upper end clamping groove and a lower end thread is adopted for the bare-head cable, so that the reliability of insulation plugging is ensured.Internally designed into two parts, During plugging, the cable connector lug is inserted into the insulating rubber cap, the clamping groove in the upper end in the rubber cap clamps the exposed partof the cable connector lug, the threaded fastening element at the lower end rotates to fasten the cable connector, the two elements play a role in double fixing, and reliable insulation and pluggingof the cable connector lug are guaranteed. The mounting and dismounting are simple and the working efficiency is improved. The insulating tape can be used repeatedly, replaces the effect of the insulating tape, and is economical and environment-friendly.