Hydraulic fracturing is an important measure to increase production and efficiency of oil and gas wells. It has been widely used in oil and gas reservoir development. However there are few studies on hydraulic fracturing of hydrate deposits. In this paper we studied the crack propagation patterns and main controlling factors of hydraulic fracturing of three types of samples. The clay minerals from the sedimentary layer of the South Seawater region were used to prepare sediment skeleton samples, hydrate sediment samples, and hydrate-ice sediment samples. The experimental results show that the fracturing pressure of the clay deposits is basically the same, the fracture pressure of the sediment skeleton is low, and the occurrence of hydrate and ice crystals in the skeleton can significantly increase the fracture pressure. During the hydrate structure fracturing process, the crack expands under the combined influence of the fluid pressure and thermal stress and has a significant delay effect. Prolonging the injection time and providing a good contact between the fluid and the deposited layer will assist the heating of the hydrate layer causing hydrate decomposition, which can significantly reduce the fracture pressure. Besides, when the hydrates coexist with the ice layer the crack propagation is mainly affected by the heterogeneity and strength of the ice layer. The structural defects of the ice layer will induce the development of complex lateral cracks. The research results can be useful for understanding the extension law of hydraulic fractures in hydrate sediments, exploring the application of fracturing technology to hydrate deposits, and increasing productivity of hydrate development wells.