In response to the limitations of random crack development and poor fracturing effect of circular boreholes in static fracturing of rocks， quadrilateral holes with the potential of stress concentration and directional fracturing were proposed as boreholes. The static fracturing mechanism based on quadrilateral holes was studied， and the fracture effect of the specimen was quantitatively analyzed according to the sharp angle stress and energy utilization efficiency. Meanwhile， the dynamic fracture process was monitored by digital image correlation technology. On this basis， PFC2D was employed to investigate the influence of borehole angle and double-hole spacing on the fracturing effect. The results indicate that the crack propagation direction of the quadrilateral hole is controllable， and fracture occurs along the extension line of its acute angle bisector. According to the displacement cloud map of the sample during the surface crack propagation process， its fracture process can be divided into three stages： initial stage， development and propagation stage， and connection stage. The stress concentration effect of boreholes is related to their shape and sharp angle. The stress growth rate reaches its maximum value when the sharp angle of the trapezoid is 30°， indicating the best stress concentration effect. The borehole shape has a relatively small impact on energy utilization efficiency. In contrast， the energy utilization efficiency of trapezoidal holes is slightly higher than that of diamond holes， with a difference of less than 5%. Furthermore， the change in the sharp angle of the borehole has a significant impact on energy utilization efficiency. When the sharp angle decreases from 60° to 30°， the energy utilization efficiency of diamond holes is increased by 19.63 percentage points， and that of trapezoidal holes is increased by 17.63 percentage points. In the single-hole simulation test， both diamond and trapezoidal holes have the maximum crack width and the best overall fracture effect at a sharp angle of 60°. In the double-hole joint fracturing simulation test， the optimal fracture effect is achieved when the spacing between the double diamond and trapezoidal holes is one-third of the length of the specimen.