Abstract: In order to determine primary factors affected to the difference distribution of the seam gas content in No.5 seam in Daning-Jixian Area, based on the ge ological factors affected to the comprehensive selected gas content, a grey relevant analysis method was applied to quantitatively analyze the influence degree of each geological factor affected to the gas content distribution.The results showed that the relevance degree of each influence factor and gas content was 0.512 550 .843 29 a nd was over 0. 5.Among those, the relevance degree of the underground water mine ralization was max and the relevance of the other factors would be less different.Th e results showed that the primary geological factors in the area would be favorable to the formation of the No.5 seam high gas features, the primary factors of the gas C ontent difference distribution would be the hydrogeology conditions under the structure role control and the control role of the other factors would not be obvious.