This work aims to select optimal shot peening process parameters so as to realize the minimum shot peening time and maximum energy efficiency by considering energy efficiency of shot peening process as a whole. Material removal volume during random shooting was obtained by analyzing arrangement of projectile group in one symmetry cell model and average crater area formed by each projectile when certain coverage was reached, and energy utilization efficiency was further obtained. With shot peening inlet pressure, projectile diameter and projectile flow rate as variables, were taken as process variables, an optimization model was established for shot peening process parameters to minimize shot peening time and maximize energy efficiency at certain coverage rate. A coupling gas-solid CFD-DEM simulation model was established for shot peening to obtain relationship between outlet projectile velocity and process parameters. Sixteen groups of simulation experiments showed that process parameters of the 4th group were the optimal combination of shot peening parameters: inlet pressure intensity of 0.5 MPa, projectile diameter of 1.0 mm, and projectile flow rate of 0.6 kg/s. This simulation model can establish the relationship between outlet projectile velocity and other process parameters, and the optimization model can allow for both efficiency and energy utilization rate, select optimal combination of shot peening process parameters and provide guidance for decision making regarding shot peening parameters.