Abstract: in order to discuss the gas intital emissio diference and the control mechanismn of coal with dfferent damage degresstaking Wangzhuang Mine in Lu an Maining Area as an example a test and measurement was conducted on the gas itial emission velocity &P of different paricle sizeinsitu stoucture coal and tectonic :oal.With the test resuits of the porosity and contact angl,the paper discussed the infuence mechanism of the paricle size and surace tension to 4P.The study foundthat the fectonic fatre role would have high infuences to the adsorption l/desorption and dfisity of the cal.T'he adsorption pores increased,the coal matix suracetension inreased and adsoption capacity increased, hich would not be favorable to the gas desorption.The open pore numbers at the large pore size section were increased and would be favorable to the gas diffision. The coresponding relationship between the cealstoucture and &P would be a reverse coesponding relationshp n a certain paricle size range(0.75~ 0.90 m).The cal with differen falre degree and the paricre size affected to the gas intial emission velocity mainly realized with the pore and cracking's infuence weight vaiation change. .When the coal cuting particle size was over ·.90 m,the cracking system would be the majorfactor affcted to the gas emission.W/hen the prticle size was less than 0.75 mn.,the porosity content woud be the major facor.The stuty resuts would have certan theoreticasignificances to coal and gas outburst mechanism and prevention.