Abstract: Fracture development and particle migration in hydrate reservoir induced by hydrate dissociation and gas production commonly occurr during marine hydrate exploitation, significantly affecting gas production efficiency and sand production characteristics. Exploring its internal law is crucial for safe and efficient hydrate exploitation. A visualization device, incorporating visual monitoring and particle image velocimetry to facilitate real-time observation of reservoir behavior during hydrate dissociation, is developed. Dissociation tests at varying depressurization rates and sediment particle sizes are conducted to explore the characteristics of fracture development induced by gas production and particle migration. Results indicate that hydrate occurrence state and reservoir structure significantly affect the fracture development pattern and evolution. Gas produced from the dissociation of hydrate zones tends to gather in occurrence areas, forming gas pockets that promote fracture development. Microfracture-rich zones often experience fracture extension due to gas migration and accumulation, further driving fracture development. With increasing depressurization rate, the fracture size increases, fracture initiation position deepens, the vertical dip angle of the longest fractures decreases, and the fracture number increases. When the overran particle size increases, fractures tend to form at great depths while the number decreases. In addition, with a higher depressurization rate, the proportion of high-speed moving particles in the vessel increases significantly. This causes a notable expansion of the particle migration zone, and intensifies the disturbance range of hydrate-bearing reservoir.