Abstract: Based on the face of Ⅱ884-1 in Luling mine，the main roof breaking and stress variation under the conditions of different igneous rock was simulated and the results achieved are as follows：Under the condition of the same thick main roof，the more area the igneous intrusive，the more the peak strain of the pressure cells which is at the roof and floor is.When the igneous intrusion area is equal，the peak strain of the pressure cells is almost same.When the thickness of igneous rocks was increased，the distance of first breaking and cycle breaking increase accordingly.When the igneous intrusion area is the same and the thickness is not，the more the igneous rock thickness is，the higher the peak strain is.The research results not only provide a basis for roof control design and roof processing in the face，but also a technical reference for the movement and breaking of the roof under the conditions of igneous intrusion.

Key words: Roof treatment, Igneous rock, Main roof, Invasion, Breaking