Based on the universality of direct method testing coal seam gas content, the importance of gas content calculation accuracy of loss amount influencing gas content, the desorption laws of full drillings coal samples under the different pressure conditions of the laboratory were measured, different sampling time to calculate the amount of gas content loss was selected, the gas content of the different sampling time correction factor based on the original gas content was settled. Reasonable sampling time and the gas content of the correction factor test results can accurately calculate the original seam gas content, which are important implications for the future of the mine outburst prevention work.