Natural gas hydrate is a relatively realistic alternative energy source to conventional fossil fuels with considerable reserves. Natural gas hydrate sediments are widely distributed in marine sediment on continental margins. In this study, a numerical modeling method for sediment containing nodular gas hydrates is developed using the two-dimensional discrete element simulation software. The effects of saturation, confining pressure, and nodule radius on the mechanical properties of heterogeneous nodular gas-hydrate-bearing sediment were analyzed using the stress-strain, fracture development, and partial body strain curves, as well as force chain distribution. The results indicated that the mechanical strength of sediment containing round nodular gas hydrates was proportional to the gas hydrate saturation and simulated confining pressure. When hydrate saturation was low, the failure strength of the gas-hydrate-bearing sediment diminished as the nodule radius increased. The simulations showed that variations in sediment porosity influenced the development and evolution of the shear band, resulting in higher porosity around the shear band. These results were analyzed from the perspectives of saturation and confining pressure to determine the failure and deformation law of simple nodular gas hydrate-bearing sediment and provide theoretical support for the subsequent study of the exploitation method of shallow buried deep gas hydrates.