Based on the strain tests of similar materials in laboratory， this research focus on crushing mechanism under expansion pressure of special-shaped holes with sharp angles， such as regular triangle hole， isosceles right triangle hole and 120° top angle isosceles triangle hole. On this basis， particle flow simulation is employed to find out the optimum angle of directional cracking effect， the optimum spacing of double holes and the influence of rock strength on fracturing effect. The results show that the crack initiation and fracture time of the sample under pressure of special-shaped holes are shorter than that of round holes， and the crack development is controllable since it is always along the extension line of sharp Angle bisector. According to the change of strain， the test can be divided into three development stages. In the steady development stage， the strain growth rate in each direction has nearly no difference. In the rapid increasing stage， new fracture surfaces are formed widely and show certain directivity. In the weak stage， recurring fractures result in energy dissipation and a sharp drop in strain. The numerical simulation shows that the best orientation effect occurs when the angular spacing is 7 times the length of the equilateral triangle side， and the rock strength has a exponential relationship with the cracking effect.