Abstract: in order to have the foo failure develogment features of the first coal mining face in No. 8 seam of Lijiazhuang Mine in Litu Mining Area,the numercalsinulation and the ste measurement combined metod was appied to study the developmen status and depthof the foo falure and cracks in No.80101 frst coal mining face and the foo falre depth develogment features undear th different mining with.Accoding to the distinguishing basis of the pressurized water,there were fivegroups ofthe sie meaured data of the crack development depth from the foo falre delection hole detemined.The numericalsnmulation results showed that withoutany infuences of the mining stress rom the neighboring minin face. the foor failre depth development of he frst coal minin face was small nd the foor falure wasin a reversed saddle shape along the face strikce. Thatis to say that at the face ends.the failure depth of the two side foors was max and the cutward in'ination of themax failure zone was mainl in a shearing falure Thefalire depthat the midtle of the coal mining face was small and was mainly i a tensile falre. The falure depthof the foor was highly affected by the with of the coal mining face and the mining falture depth ofthe foor and the wiath ofthe coal mining face were varied i a lneatThe site measured result showed that the foorfalre depth of No.80101 frst coal mining fae in Liujazhuang Mine was 16.32~16.2 m and thevalidt f he umeical simulation was approved and the basic information would be provided to the pressurized mining in the lower group seam in liliu Mining Area.