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Characterization and evaluation of microscopic pore structures of natural gas hydrate reservoirs are important for the identification and exploration development of gas hydrate. In order to more effectively characterize the microscopic pore structure of gas hydrate reservoirs and conduct relevant characterization analysis, digital rock model was constructed based on high-resolution CT scanning of gas hydrate reservoir rock samples. The relevant pore structure parameters were obtained by numerical simulation methods. The pore structure was characterized and analyzed by the fractal theory of porous media. High-resolution CT scanning and numerical simulations of rock physics show that the pore size of the rock sample is mainly distributed within the range of 1-5um. The rock sample is mainly based on microscopic pores, and the microscopic pores provide most of the pore volume. Fractal dimension analysis results show that the fractal dimension of the gas hydrate reservoir rock presents a distinct linearly segmentation feature. The fractal dimension of the rock pores in the interval I ranged from 2.214 to 2.714, indicating that the small pores were evenly distributed in the interval I, and ranged from 2.869 to 2.988 in the interval II, indicating that the pore distribution uniformity was poor in the interval II. In addition, there is a certain correlation between the pore fractal dimension D1, D2 and the porosity, permeability and average pore radius of gas hydrate reservoir in a whole. The fractal dimension D1 is positively correlated with porosity, permeability, and average pore radius. The fractal dimension D2 is negatively correlated with porosity, permeability, and average pore radius. Dong Huaimin https://orcid.org/0000-0002-1175-1956 • Fractal theory combined with digital rock were applied in the characterization and evaluation of the complex pore structure of gas hydrate reservoir. • Fractal dimension analysis results show that the fractal dimension presents a distinct linear segmentation feature. • There is a certain correlation between the pore fractal dimension D1, D2 and the porosity, permeability and average pore radius in a whole. [ABSTRACT FROM AUTHOR]