In this work, the effects of air-borne particle-particle interaction on the erosion rate and erosion pattern of a specimen surface have been studied both numerically and experimentally. For the numerical modeling, the Discrete Empirical Model for particle-particle collision and Oka[U+05F3]s model for material erosion are employed and implemented within the framework of Computational Fluid Dynamics. The focus is on the effects of three main parameters, that is, impinging angle, sand particle flux and impinging velocity on the erosion mechanism and erosion rate with or without particle-particle interaction. It is shown that the simulation results with particle-particle interaction agree well with our experimental measurements, but they are significantly different from those without particle-particle interaction. It is revealed that the particle-particle interaction leads to the formation of a shielding layer above the sample surface to protect the surface by reducing or damping the impact of incident particles. This shielding effect is, however, strongly influenced by impinging angle, sand mass flow rate and impinging velocity. The present study may provide important engineering insights and guidelines for minimizing the air-borne particle erosion on equipment.