This study presents the experimental apparatus of flow loop type to investigate the hydrate plugging phenomena. The experiments for formation and dissociation of methane hydrate were conducted using the experimental apparatus setup in this study. Through the experiments, ( gas + water + hydrate) three-phase equilibrium conditions were measured and enthalpy change in the dissociation process was analyzed based on the equilibrium results. The equilibrium conditions and the enthalpy of dissociation have been found to be consistent with previously published reference data. To examine the effect of hydrate formation under the flowing condition, experiments were carried out at varying flow velocities under a constant pressure. As a result, hydrate forming temperature tends to increase linearly with increasing flow velocity. Therefore, it was verified experimentally that flow velocity can be considered as one of the significant factors triggering the increase in the formation temperature.