Today, humans are dealing with two urgent issues: energy security and environmental pollution and finding sources to replace traditional fuels such as gasoline and diesel that are part of human interest. Lignocellulose biomass can be obtained through a variety of basic chemicals or intermediates that generate energy, such as ethanol, butanol, and dimethylfuran. 2.5-dimethylfuran (DMF) is considered a potential alternative fuel because it is a water-insoluble substance used as an additive mixed with gasoline fuel. Formerly, there have been many studies on combustion engines and emissions properties using the DMF-gasoline blend, especially SI engines. However, there has been no published research about the optimal ignition timing advance of SI engines when using these blends. This paper present how to determine the optimal ignition timing advance of SI engines using DMF-gasoline combinations with AVL-Boost simulation software. The simulation conditions were set up at 50% load, and speed at 2500 and 3000 rpm using blends are DMF20, DMF30, and DMF40 (corresponding with the DMF ratio in DMF-gasoline blends is 20%, 30%, and 40% in volume). The simulation result shows that the optimal ignition timing advance of SI engines using DMF-gasoline blends at a 2500 and 3500 rpm speed corresponding with 23 and 31 crank angle degrees (CAD) (reduce 2CAD compare to when using pure gasoline). At these optimal ignition timing advances, the power engine, torque, and thermal efficiency (BTE) reach its maximum value, while the fuel consumption rate is also lowest.