In order to study influence of damage capability and permeability in process of high speed water jet, methods of theoretical calculation and numerical simulation were adopted,  permeability breaking coal-rock technology was studied by the method of high speed water jet. It was observed that velocity distribution was different when high speed water jet injecting different form coal. Injecting flat seam, water flow was distributed as T, injecting inside drill, water flow was distributed as arcuation. More high speed water jet, more high speed corresponding same position, effect of injecting inner drill and permeability were better than injecting flat seam, effective radius was up to 2.6 times.