Because of the complex nature of coal reservoirs, no determined method can clearly assess their pore-fracture structure. This paper combines a fractal method with the transverse relaxation time (T-2) of nuclear magnetic resonance (NMR) to study pore-fractures in a coal reservoir. Based on 10 coal samples with vitrinite reflectance (R-o,R-m) in the range 1.32-2.43%, the pore size/volume distribution from mercury intrusion porosity (MIP) and NMR was compared, revealing that a strong correspondence exists, and that the correspondence for pore diameter of >100 nm is better than that for pore diameter of <100 nm. Pore diameter of 100 nm is also the division for adsorption and seepage pore, which corresponds to 0.29 ms of T-2 value. Furthermore, fractal dimension and pore-fractures by NMR are discussed. The pore-fractures in coal can be divided into four types based on the T-2 spectrum of NMR: micropore, mesopore, macropore, and fracture, corresponding to <0.29, 0.29-12, 12-100, and >100 ms of T-2 values, respectively. Fractal dimensions for these four types of pore-fractures (D1, D2, D3, and D4) were acquired and ranged from -2.84 to -2.41, from 2.71 to 2.89, from 2.73 to 2.95, and from 2.87 to 2.99, respectively. However, D1, -2.84 to -2.41, for micropore does not conform to the definition of fractal theory because of bulk fluids and diffusion in internal field gradients in micropore. D-NMR, D-MIP, and D-N are fractal dimensions by NMR, MIP, and N-2(77 K), presenting a relationship of D-NMR < D-N < D-MIP. D-NMR shows different correlations with the percentages of different pore-fractures. Strong correlations between percentages of pore-fractures and vitrinite reflectance (R-o,R-m) show a huge change at R-o,R-m = 1.8-2.0%, which indicates a third coalification jump. When permeability is over 0.025 mD (millidarcy), permeability also presents a positive relation with fractal dimension D-NMR. Therefore, the NMR fractal method of studying the heterogeneity of pore-fractures in middle-high rank coals has both feasibility and practicability. The NMR fractal method provides a more reasonable and reliable way to characterize coal pore-fracture structure qualitatively. Meanwhile, the NMR fractal method provides a new perspective to explore the process of coalification jump.