Abstract: in order to study the porous stucture differences of the soft coal and hard coal af cted to the coal and gas outburst a mercury inrusion porosimetry was appied to the experiment study on the soft and hard anthracte cal of Gulqing Mine The porous structure features of the sot.cal and hard coal vere anajzed and compared. The results showed that the mercury-injection curve and mercury-ejecion curve wer all not coincided,the pare ditibution waswide,the pore volume of the soft coal micropore was mostly developed,the pore area of the micropore wa taken over 98% an favorable for gas storage. But the big.medum pores and cacks to make up the permeable volume were less developed,a'lagena type pore existed caused the poor permeatility of the sot cal nd would not favorable to the gas dfifisionand ransfused. The pore volume ofthe hard coal micropore and araof the microporeboth were lss developed and the vistile pores and cracks were well eveloped.Thus.the permeablityof the hard cal was beter than the sot cal and would be favorableto the gas fiow and gas drainage. Generallytheoutbust would be more easly occurred in the soft coal than hard coal.