Combining experiment and simulation, spray characteristics of CeO2 nano-fuels and diesel including pen-etration distance, cone angle, and Sauter mean diameter (SMD) were investigated at various working con-ditions to reveal the effect of nanoparticles on the fuel spray. The correlation degree between spray characteristics and injection pressure, ambient pressure, and mass concentration of nanoparticles was assessed using the grey relationship analysis. Due to stronger axial diffusion and relatively weaker radial diffusion, nano-fuels showed a longer spray penetration, a smaller cone angle, and a larger SMD than die-sel. The difference in spray characteristics between nano-fuel and diesel widened along with an increase in mass concentration. Additionally, the kinetic energy of spray, air resistance, and entrainment were sus-ceptible to injection and ambient pressures. In general, higher injection pressure increased spray pene-tration and cone angle while reduced SMD. Oppositely, higher ambient pressure decreased the spray penetration while increased the cone angle and SMD. Among the three factors, the injection pressure had the greatest effect on spray characteristics, followed by ambient pressure and then mass concentration. (c) 2022 Elsevier Ltd. All rights reserved.