Abstract: The determination of coal gas content was the basic work to forecast the gas emission of the working face and mine. In general, the gas existed in coal and rock in sorption state and free state. The experiment showed that the gas adsorption amount of limestone body was very little. In this paper, it mainly analyzed the gas occurrence state in limestone body, studied and determined the indirect calculation method of gas content in limestone body, and forecasted the gas emission of the working face, achieved higher prediction accuracy.