The utility model relates to a small-bore rubber anchor cable grouting plug which comprises an annular liquid cavity, a liquid injection pipe and a grouting connecting pipe. The grouting connecting pipe communicated with the annular liquid cavity is arranged on the upper side of the annular liquid cavity, the liquid injection pipe communicated with the annular liquid cavity is arranged on the lower side of the annular liquid cavity, the annular liquid cavity is formed by a plug cover, a plug sleeve and a plug body, the plug sleeve is arranged at the upper end of the plug body, and the plug cover is arranged in the plug sleeve. The small-bore rubber anchor cable grouting plug has the advantages that the structure is simple, and use is convenient; meanwhile, due to the fact that the diameter of the plug sleeve is identical to that of a drilled hole, prestress total-length anchoring construction can be completed without additionally drilling a large hole, and the problem that the anchor cable construction prestress total-length anchoring construction quantity is large is solved; meanwhile, an anchor cable adopting the grouting plug can be grouted after a front head in a lagging mode, the normal construction procedure of the front head is not influenced, and the project progress is not influenced.