Abstract: Particle impact drilling is a new kind of breaking technique, which uses high-speed spherical carbide steel particles and jet flow as a primary means and mechanical breaking for assistance. For flow channel of straight-taper nozzle, a mathematical model of velocity and acceleration in the process of particle and jet flow breaking was established. Through the analysis of the energy absorption law in the impact process, the functional relationship of single particle velocity, particle volume and broken rock volume was established. The results were verified on LSTC-DYNAMIC simulation platform. A particle and jet flow breaking experiment with four particle diameters ranging from 0.8mm to 1.4mm was conducted based on self-developed particle impact rock breaking testing apparatus. The matching relationship of the particle volume, impact velocity, flow velocity and broken volume was verified, which provides supporting data and a theoretical basis for the promotion of this technique.