A link connecting structure includes two outer link plates and two inner link plates. An inner side of each outer link plate is formed with a concave portion between two first coupling portions at two ends thereof. A connecting surface is connected between each first coupling portion and the concave portion. The connecting surface is gradually tapered inward from each first coupling portion toward the concave portion. An outer side of each inner link plate is provided with a pair of bent portions each extending from an outermost edge of each second coupling portion toward the connecting surface. A gap is defined between each bent portion and the connecting surface. The gap is less than the minimum thickness of a narrow tooth of a chainring, thereby preventing the tooth from being jammed in the gap.