Abstract: Coal geology is a branch of geology about coal formation and composition, associated minerals in coal bearing stratum, and coalbed gas. The research content of coal geology has changed gradually with safe-mining and clean utilization of coal resources, evaluation and exploitation of coalbed gas. The development frontier of coal geology was analyzed based on 717 papers published in International Journal of Coal Geology from 2011 to 2015. It was found that coalbed gas resources evaluation and coal reservoir physical properties research are the most attractive research fields in the world recently; minerals and trace elements in coal have been paid enough attention to; researches on coal petrology and organic geochemistry related to coal forming and utilization, environmental issues caused by coal combustion and spontaneous combustion, depositional environment and coalification, GIS (geographic information system) and environmental monitoring of mining area, coal mine gas, coal mine geological structure, coal mine water, and coal pyrolysis have been continued; resources evaluation and exploitation of shale gas have been paid more attention to.