The impactrotary drilling process of rock drilling jumbo is modeled and simulated; and the influences of different drilling parameters such as propulsion pressure, impact pressure and rotary pressure on drilling efficiency are analyzed to obtain the matching relation of drilling parameters in the optimal drilling state. And then an automatic matching hydraulic control system for drilling parameters based on propulsion pressure difference and rotary pressure is designed. The results show that: (1) The impact pressure can be adjusted automatically with the change of propulsion pressure difference. (2) The system can identify the state of drill jamming according to the change of rotary pressure, and can respond to motions such as slowing down drilling speed, stopping propulsion and countermarching correctly.