Abstract: This paper utilized the numerical simulating technique to study the crack deformation of coal in microwave heated,and respectively achieved the heating effect of crack coal in the microwave heating mode and traditional heating mode.The result shows that microwave heating temperature field distribution is chiefly characterized by uneven,the highest temperature is in the center and the lowest at the surface,the characteristic of traditional heating temperature field distribution contrary to microwave heating.As a result the strains and stresses of coal crack is also different,there are more pressure stress around the fracture surrounding and crack will begin to shrink in microwave heating and the more tensile stress and expansion in traditional heating,but the pressure stress is much more than the tensile stress;Heat source the more close to the fracture the pressure stress is more obvious,and the tensile stress is obvious.