Abstract: Natural gas hydrate is widely regarded as a potential new energy source and a possible trigger of environmental issues. However, the research community of gas hydrate are still faced with difficulties in quantifying pore-scale structures of the hydrate-bearing sediments. Based on our observation, the difficulties can be well solved by using fractal theory. In this paper, we firstly made an introduction to the basis of the fractal theory, followed by a review of fractal theory applications in the gas hydrate community. Then, a fractal theory for quantifications of the effective pore space in hydrate-bearing sediments is presented, and a summary and some suggestions for gas hydrate related fractal researches in the future are finally provided.