Rotary percussion drilling is currently most used efficient rock breaking technology in deep hard formations drilling and the effect is remarkable. Based on vibration theory and the consideration of the gravity of rack, the mathematical model of rock vibration under impact load was established. Renormalization method was used to get the solution and MATLAB software was used to analyze the influence of various parameters on the vibration of the rock. Finally, laboratory experiments were conducted to verify the analytical results. Research shows: The movement of rack under drill bit’s impact is mutual interference vibration between two harmonic vibration. The vibration amplitude of rock as well as the vibration velocity becomes larger with the decrease of rock density, the decrease of rock stiffness and the increase of the impact force. There is an inherent frequency of rock. Vibration of rock becomes more intense with the decrease of the difference between impact frequency and the inherent frequency. When high impact frequency equals to the inherent frequency, the vibration amplitude and vibration velocity reach the largest and this is resonance. For revealing the crushing mechanism of rock under dynamic load and guiding the design of impact tools, analysis of the response of rock under impact loads is of great significance.