Abstract: Based on the water and gas outburst accident of No.2 surface borehole in Yangliu coal mine, the combination relationship between the two igneous rock s was analyzed using the combining method of theoretical analysis and numerical simulation, strata cracks evolution law under thick hard igneous rock during protective layer mining was researched, and the reason for water and gas outburst accident of No.2 surface borehole was analyzed. The results demonstrated that the magma int rusion had a specific effect on coal seams. There are large quantities of pyrolysis pores in coal seam nearby igneous rock, which make the adsorption ability of coal sea m enhance. The thick hard igneous rock controls the overlying strata movement, a large number of separations and fractures exist in the separation zone for a long tim e, which provide migration channels and enrichment area for relief-pressure gas and water. The igneous rock releases a lot of elastic strain energy when fracturing sud denly, this induces to the occurrence of compound dynamic disaster. Based on the research results, the prevention countermeasures and suggestions were put forward.