Aroma stability is one of the core evaluation indicators of Baijiu quality. Studies have conventionally focused on polar flavor compounds, such as esters, alcohols, and acids, with insufficient attention paid to the roles of common nonpolar alkanes. To investigate the effects of alkanes on the aroma of Baijiu, a combination of liquid-liquid extraction and modern instrumental techniques, including gas chromatography-mass spectrometry and gas chromatography-olfactometry-mass spectrometry, was performed. A systematic analysis of the aroma components was carried out, together with odor activity value calculation and sensory evaluation. A sensory evaluation of Baijiu samples from different years was conducted for 0~12 h under alkane concentrations of 0.61~1.67 mg•L-1. The results showed that the aroma intensity of Baijiu samples in each group decreased with time. The aroma intensity of the alkane group was significantly higher than that of the non-alkane group (P<0.05), and the rate of decline was slower, even at 12 h. In the Baijiu samples with high ester contents, alkanes exerted significant stability and synergistic effects on fruity and floral aromas; for Baijiu samples with high alcohol contents, alkanes mainly played a role in delaying aroma attenuation. Alkanes are speculated to play a synergistic role in aroma fixation through multiple pathways, including by forming a molecular association system with aroma components, increasing the viscosity of the Baijiu body to slow diffusion, and adjusting the polarity of the matrix to reduce the vapor pressure. This study provides a theoretical basis for the precise regulation and quality improvement of Baijiu flavor.