Abstract: Exploring the key flavor compounds of the strong-aroma grapefruit oolong tea and figuring out how different roasting treatments affect its quality. Based on previous orthogonal test results and sensory evaluation, three samples with different quality levels were selected（highest sensory score: O2-1, middle: O2-2, lowest: O2-3). Using physicochemical analysis and gas chromatography-mass spectrometry（GC-MS), combined with chemometrics, we systematically compared their sensory quality, main taste components, and volatile compounds. The results show that the tea sample with the highest sensory score was processed with the following technique: 12 hours of aroma infusion, 60% flower addition, and drying temperature of 90℃（sample O2-1). This sample had a strong grapefruit flower aroma and a rich, mellow taste. There were significant differences in the tea polyphenol and caffeine content among the samples with different aroma infusion treatments（P＜0.05); A total of 233 volatile compounds were detected in the strong-fragrance pomelo-scented Tieguanyin, mainly esters, terpenes, and heterocyclic compounds, with 62 of them having a relative content over 1%. Linalool, dehydrolinalool, and indole are the main substances responsible for the pomelo blossom aroma. By combining relative odor activity values with sensory evaluation, it was found that 2-isopropyl-3-methoxypyrazine and 2-thiophenemethyl mercaptan are the main sources of the green and fishy notes in dry tea, while 5-ethyl-3-hydroxy-4-methyl-2(5H)-furanone, methyl benzoate, and others are important compounds that give the grapefruit-scented Tieguanyin its floral and fruity aroma. The aroma changes observed in sensory evaluation basically match the trends in actual measured volatile compounds. This study identified the key flavor compounds of grapefruit-scented Tieguanyin and the optimal roasting process, showing how different roasting treatments affect its flavor, providing a reference for improving processing and quality.