Using CFD, the effect of burner angle on an aluminum rotary furnace performance is studied in the present study. Turbulent non-premixed combustion of natural gas and oxygen, radiation, furnace rotation, aluminum smelting and aluminum burn-off are considered in the proposed numerical model. According to the distinct phenomena occurring in an aluminum rotary furnace, the model divides the furnace into three zones: refractory lining, combustion zone and melt zone. Only heat can be transferred through interfaces of zones and mass transfer through them is not considered in such furnace modeling. Numerical simulations regarding burner angles form 0ᵒ to 15ᵒ revealed that the higher burner angles enhance the fuel and oxygen mixing and increases the resident time of combustion gases in the furnace atmosphere, which consequently improve the furnace performance and lower the aluminum melting rate. However, the simulation results also showed that burner angles more than 10ᵒ are not applicable due to refractory lining overheat. It was showed eventually that changing burner angle from 0ᵒ to 10ᵒ decreases furnace operation time by 35 minutes and increases furnace thermal efficiency from 65% to 74.7%.