Coking coal resources are very scarce, but the factors causing its scarcity are unclear. The contingency table analysis method was used to study the correlation between coking coals and coal-forming plants, coal-forming age, sedimentary environment, metamorphic power and geothermal gradient. The results show that, coking coal only exists in the partial coal-forming period of coal gathering period in China; the gel-forming material in coal-forming plants is a necessary condition for coal formation; the lake sedimentary environment has a high probability of coal formation; after above conditions are satisfied, metamorphic dynamics and paleogeothermal conditions are the key factors affecting the evolution of plants into coking coal. The research can provide a reference for better estimation of coking coal reserves and protection of coking coal resources.