Abstract: Macroscopic and microscopic morphology of the formation of HCFC-141b gas hydrate were obtained by a set of low temperature experiments. The macroscopic morphology was recorded by a digital video camera, and the microscopic morphology was recorded by a microscope with a camera, magnified by 200 times. The test results indicated that the nucleation of gas hydrate had started at the two interfaces:between liquid water and liquid refrigerant or between liquid water and vapor refrigerant. The nucleation then gradually expanded to the whole boundary and formed a layer of hydrate. After that, refrigerant liquid diffused continuously into water through hydrate layer and formed new hydrate. The growth rate of gas hydrate was obtained from the microscopic photos and was compared with that in the former external cooling experiment.It was shown that disturbances could enhance the contact dimension between refrigerant and water phases.