Oyster sauce (OS) is a common seasoning in Asian countries. Here, four types of OS with different components and ingredients were characterized by the switchable GC/GC × GC-olfactometry-mass spectrometry (SGC/GC × GC-O-MS) and sensory evaluation. A total of 27 key aroma-active compounds were screened by FD factor and OAVs in OS. Of them, pyrazines were predominated, 2,5-dimethyl-3-ethylpyrazine had the highest OAV and FD factor. Sensory evaluation showed that the overall flavor profile of OS is primarily composed of nutty/roast, caramel/sweet, cooked potato-like, fruity, burnt, and unpleasant notes such as rancid, mushroom-like, and fishy. Moreover, soy sauce exhibited a great impact on OS aroma. The principal component analysis (PCA) results based on the OAV values of key aroma-active compounds were consistent with the sensory evaluation results, suggesting that PCA based on the above method could accurately cluster and distinguish the samples with different aroma profiles. The odor notes of burnt, fruity and caramel-like/sweet contributed to WDM and JC clustering. Similarly, roast/nutty, cooked potato-like, and unpleasant odor notes contributed to clustering of LKK and HT.