Abstract: In order to solve the problem of large initial caving step, the deep hole presplitting blasting technology had been used in interconnection of mining face t 0 decrease the initial caving step. According to the natural situations and the mining technical conditions of No. 11 coal seam in No. 2 Underground Coal Mine of Pingsh u0, the initial main roof caving step of initial mining face was calculated based on the mechanical model which the main roof was regarded as a clamped rock beam. Th e pressure detection and analysis results showed that the first collapse step was merely 15. 6 m after weakening processing and hanging area of the main roof above g oaf was reduced, which meaned the danger of large pressure while the roof caved was prevented effectively. The safety during downward mining the initial mining face i n the underlying seam of contiguous seams had been ensured.