For the problems of large block size and low slag throwing efficiency in cut blasting of hard rock tunnel，the numerical model of compound wedge-shaped cutting was established using the LSDYNA. The blasting effect of compound wedge cutting under different hole depth and delay time was analyzed. The results show that the middle hole can be utilized to reduce the large lump rate and improve the breakage effect of rock. When the vertical depth ratio a of middle hole to cut hole is 0.7， the rock can be broken satisfactorily. The rock breakage effect gradually decreases with the increase of the ratio a. When the middle and inclined hole are detonated at the same time，the rock breakage is most severe. The delay initiation of inclined hole has little effect on rock breakage，however it can improve slag throwing effect. The research results has been used to improve the degree of rock fragmentation in tunnel blasting，ensuring the construction progress