Low-rank coals in eastern Junggar Basin, China were studied to understand how the first coalification jump affects their properties. Lignite coal has more inertinite, larger pores, and better connectivity compared to candle coal. As coal matures, moisture, porosity, and permeability decrease. Lignite has more small pores, while candle coal has larger pores. Despite having lower surface area, candle coal has less methane adsorption capacity due to its composition. Low-field NMR showed differences in pore structures between the two coals. Overall, this study helps us understand how coal changes as it matures and how it affects coalbed methane development.