Abstract: This study aimed to establish a novel and efficient analytical method based on magnetic expanded graphite (MEG) solid-phase extraction coupled with gas chromatography-mass spectrometry to address the challenge of accurately determining the trace characteristics of the aroma compound 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN) in Riesling wines. The MEG adsorbent was prepared via a facile physical blending method, and its physicochemical properties were systematically characterized. Additionally, the key parameters affecting the magnetic solid-phase extraction (MSPE) pretreatment were optimized. Furthermore, density functional theory calculations were employed to investigate the adsorption mechanism at the molecular level. The results indicated that the method exhibits good linearity in the range of 0.05~100 ng/mL (R²=0.9943), with a limit of detection as low as 0.01 ng/mL. Theoretical calculations confirmed that the synergistic effect of van der Waals forces and π–π stacking (binding energy: −0.84 eV) was the key driving force for the efficient adsorption of TDN. The proposed method was successfully applied to the analysis of various Riesling wine samples, demonstrating high efficiency, accuracy, and reliability in the quantitative analysis of the target compound. This study not only provides a rapid and sensitive analytical tool for TDN but also offers new insights guided by theoretical calculations for the design and application of novel enrichment materials for food flavor compounds.