The invention relates to an inner yarn guide rod assembly of a single-pipe yarn feeder. The inner yarn guide rod assembly is characterized by comprising a yarn guide rod and a yarn guide ring, wherein the yarn guide rod comprises a long and flat sheet part and a long round rod part; the long round rod part is internally connected onto a lower side edge of the long and flat sheet part; a plurality of yarn ring mounting grooves are uniformly distributed in the long and flat sheet part along the length direction; a mounting hole is formed in one end of the long and flat sheet part; the yarn guide ring is mounted in the yarn ring mounting grooves in a detachable manner; and a yarn guide hole is formed in the center of the yarn guide ring. The inner yarn guide rod assembly is compact in structure and reasonable in design and can provide smooth and obstacle-free guidance to yarns; and a condition that the yarns are broken is reduced, and the working efficiency and the quality of a product are improved.