Perimeter blasting is very important to control engineering quality in the process of roadway construction,and it is a common way to use slotted pipe blasting to improve the perimeter blasting effect.However,the unreasonable setting of slotted pipe blasting parameters still weakens the directional destruction effect,including the greatly damaged contour,low hole retention rate,common phenomena of over-excavation and under-excavation.In order to improve the directionality of blasting damage,the slotted pipe blasting parameters should be optimized.The reasonable blasting parameters were determined with the study of explosive slotted pipe uncoupling and different initiation positions by numerical simulation using ANSYS/LSDYNA.According to the numerical simulation results,the balance between the protection of surrounding rock mass and directional failure can be achieved when the uncoupling coefficient between the explosive and slotted pipe is 1.12.Meanwhile,the integrity of the contour line is greatly improved when the initiation positions of two adjacent explosives are changed to make the meeting position of the explosive shock waves on the same horizontal plane that shifted to 3/4 of the position between two blast holes.It can be concluded that the damage to the retained rock mass can be greatly reduced as adopting uncoupled structure between slotted pipe and charge,and changing the meeting position of stress wave between blast holes by adjusting the detonation position of charge.