An optical comb based stable frequency dissemination system is proposed and experimentally demonstrated over a multi-access optical fiber loop link. In the system, a new technique based on optical-microwave phase locking loop is designed for phase compensation. In the experiment, a mode-locked fiber laser at a repetition rate of 100 MHz is used to provide an optical source at local site, then it transmits along a 150 km fiber loop link. To testify the proposed system, two accessing nodes are measured in the loop link. The dissemination frequency instability is measured at 3.65 × 10-15/1 s and 7.8 × 10-18/1000 s at the intermediate node. The similar performance is shown at the other node. Hence, the system has the potential application in high-precision frequency transmission system via a long-haul multi-access loop link.