The use of nanoparticles has been intensively investigated to improve foam flooding in oil production. Because nanoparticles have larger adhesion energy at the air-water interface than the surfactant, they help to prevent a gas diffusion between bubbles that leads to foam film rupture. In this study, the detail investigation on the behavior of mixed-surfactant foam stabilized by silica nanoparticles (SiO₂-NPs) was conducted. The binary surfactant systems of an internal olefin sulfonate (IOS) and sodium polyethylene glycol monohexadecyl ether sulfate (C₃₂H₆₆Na₂O₅S) were selected. The impact of alkane oil with varying carbon chain length (i.e. hexane, octane, dodecane, and hexadecane) was investigated. The findings from a similar system of foam in deionized water (DI) and brine solution also presented for comparison. For SiO₂-NPs foam/brine system in the presence of oil, the foam stability increased to a maximum with respect to certainly added nanoparticles (10 ppm), and the additional surfactant is required to maintain the foam stability when the alkane chain length increases. The foam stability parameter indicated by spreading (S) and entering (E) coefficients shows that the SiO₂-NPs foam systems with the shorter-tail surfactant (mixed C_15-18 IOS) had lower the coefficient values compared to the longer-tail one (mixed C_19-23 IOS), suggesting that the structure of surfactant influents on foam stability. The findings from this study bring an understanding of the SiO₂-NPs foam/alkane oil behavior in the brine solution, which helps to select the appropriate system for improving foam flooding in EOR applications.