Cilinshan Mine of No. 15 coal seam 15103 working face basic roof was old limestone, not easy roof caving. In order to ensure mine safety production, forced caving of deep hole blasting was put forward. This blasting used No. 2 coal mine permissible explosives, main technical characteristics of blasting was using large dose of explosive load, deep hole blasting used oblique way, with innovation design of powder charge, the poisonous and harmful gas was estimated after blasting etc. The results showed that the compulsory caving blasting design achieved the expected results, the concentration of poisonous and harmful gases estimation was basically the same with actual measured data, the underground deep hole blasting of forced caving can provide valuable reference for other similar blasting.