In order to investigate the mechanism of uni-directional pedestrian flow, we organize one single-file flow experiment on a ring corridor. With 203 participants, the maximum global density reaches 4ped/m. The fundamental diagrams are given, and compared with that of the single-file experiments held in other countries. We find the pedestrians’ velocities in our experiment are close to the Indian results, and larger than German results. In the time-headway distributions, the peak gradually disappears with the increase of density. At medium densities, the upstream propagation of stop-and-go waves can be observed. The calculated propagation velocity is about 0.4∼0.5 m/s. At extremely high densities, the transition between stopping state and moving state can occur, which is similar to that found in uni-directional experiments with wider system width. In these phenomena, we find there exists one critical density, which is about 3ped/m. All these results can help to learn more about the essence of single-file pedestrian flow.