Aiming at the problem that most of the explosion energy of deep hole blasting in complex stress environment shrinks in the crushing zone and cannot be effectively used in the crack propagation of coal seam, the influence of control hole diameter on the antireflection effect of blasting is studied. Based on the mechanism of control hole under blasting load, three groups of comparative tests were carried out by using the self-built similar simulation test platform without control hole, ordinary control hole and reaming. The crack propagation characteristics, stress wave propagation and coal damage evolution law in the blasting process were obtained. The results show that the existence of the control hole can guide the blasting crack to expand along the direction of the connection between the blasting hole and the control hole, forming a penetrating main crack. At the 2# measuring point, the peak tensile strain of the reaming test block and the control hole test block increased by 36.4% and 16% respectively compared with the non-control hole test block, indicating that the increase of the control hole diameter can significantly enhance the stress concentration effect around the control hole, increase the tensile stress amplitude, and promote the formation of the cross-fracture network between the two holes. The ultrasonic inversion results show that the wave velocity reduction of each model on the S2 detection surface after blasting is 30.46%, 36.92% and 42.78%, respectively. The damage of the reaming test block between the two holes is more significant, indicating that the large-aperture control hole can more effectively improve the explosion energy utilization rate and anti-reflection range. The research results can provide experimental basis for parameter optimization of controlled blasting in high gas coal seam.