The gas-liquid-solid phase transition of hydrates is complex and has effects that are coupled with the heat-mass transfer in reservoirs; thus, this phase transition is related to the determination of flow assurance and production efficiency. The microfluidic technology applied in this research can simulate a porous medium and is an alternative to the conventional sand packing approach, encompassing real characteristics of interfaces between multiple phases, reducing the randomness of pore shape, and mastering the distribution of flow channels. The hydrate phase transition was observed directly, while the relationship between the hydrate saturation and the permeability was analyzed. The entire experimental cycle was greatly shortened and was performed at lower cost and with more convenient operation than traditional sand-packing methods. The results indicate that hydrate saturation is negatively correlated with permeability. Considering the properties of etched throats, the newly generated particles can reduce the model permeability greatly at the beginning of the hydrate formation and can ultimately block the flow channels. The detailed information presented in this study indicated that, at the initial stage of dissociation, hydrate blocks not only transformed into water and gas but also decomposed into small pieces. Gas-liquid interfaces first appeared around the hydrate block edges, and there were shrinkage cavities on the hydrate block surface during the dissociation. After complete dissociation of the hydrate, bubbles and water drops were found left in the phase of each other nearby the throat wall.