Increasing the injection pressure and using blend fuels are two strategies for ‎reducing the emission of diesel engines. Accordingly, in the present study, by ‎using the CFD analysis, the influence of high injection pressures on the non-‎reacting behavior of the liquid HFO and HFOn-butanol blend spray as an ‎alternative fuel is studied. Three different injection pressures of 1000, 2000 ‎and 3000 (bar) in a constant volume chamber of the medium speed diesel ‎engine at the temperature of 298 K have been considered. Furthermore, an ‎Eulerian-Lagrangian multiphase scheme has been used for simulating the ‎interaction of the discrete liquid phase of the fuel with continuous air phase, ‎while the Reitz-Diwakar scheme has been utilized for modeling the secondary ‎breakup. Furthermore, numerical results of spray characteristics are validated ‎with experimental data and a favorable agreement has been achieved. Based on ‎obtained results, increasing the injection pressure would cause an increase in ‎the spray penetration length and the spray cone angle and a decrease in the ‎Sauter mean diameter (SMD). However, increasing the injection pressure from ‎‎1000 to 2000 (bar) has more significant effect on improving spray ‎characteristics than an increase from 2000 to 3000 (bar).‎