Abstract: In order to study the influence degree of the floor failure in Jinhuagong Coal Mine,in accordance with the engineering practice,FLAC^3D software was used to simulate the main stress distribution and deformation of the floor during the mining of 7-4^#coal seam.By using the two mechanical parameters of main stress difference and main stress ratio,the distribution of principal stress parameters of coal floor under the conditions of one side mining and two sides mining were analyzed.The numerical simulation results show that the principal stress difference near the coal pillar is butterfly-shaped,and the principal stress ratio around the goaf is distributed in the form of enveloping circle.Through the comparative analysis of the characteristic parameters of the principal stress on the floor on one side and two sides,it is found that there is a higher concentration of principal stress difference near the coal pillar which is excavated on two sides than on one side,finally,it is concluded that the failure depth of the floor can reach 5 m and the influence depth is up to 43 m,which is consistent with the field data,the reasonableness of using principal stress to characterize the parameters,namely,principal stress difference and principal stress ratio to analyze the failure of the floor is verified.