Abstract: In order to determine the pre- drainage effect checking index of gas content critical value in the coal and gas outburst mine, according to the relationship between the gas desorption index K1of the drilling cuttings and the gas content of the seam, in combination with the gas content measuring technology, the site statistic analysis method and the outburst prevention practices, a gas content critical value was provided firstly as the pre- drainage effect checking index critical value by contr astive analysis and correction and was verified in a region of the mine. In combination with the actual condition of Shanxi Jincheng Daning Mine, the gas content critical value in the deposition normal region of No.3 seam in Daning Mine was determined as 9 m3/ t and the gas content critical value in the abnormal region of the geologica | structure was 7 m3/ t. The site practices showed that the study achievements would provide the basis for coal and gas outburst prevention.