Abstract: In order to study the gas occurrence nonlinear characteristics of deep mine, the critical depth concept of gas content which is the result of two opposite factors` comprehensive effect on coal body adsorption is proposed. The opposite factors are formation pressure and formation temperature. In No.10 Coal Mine of Pingdingshang Tian'an Coal Industry, we determine the parameters of gas adsorption constant parameters and gas content, establish the model of gas occurrence law in deep mine for demonstration. The analysis find that the gas adsorptive a value of Wu₉ coal at 920 m deep is bigger than that of 875 m, and the gas content of Ji₁₅ coal no longer increases obviously with burial depth at about 910 m, but even slightly reduced. The results show that the gas occurrence of the deep mine has nonlinear characteristics that exists a critical depth of gas content at certain depth of deep mine.