The distinctive seaweed-like aroma is a typical flavor characteristic of high-grade Shandong matcha. To obtain a sample of strong seaweed aroma extracted from matcha, high-grade Shandong matcha made from fresh leaves of Camellia sinensis cv. Zhongcha 108 was steeped at 70 °C with a 1:6 tea to water ratio. A total of 11 volatile components that contribute significantly to the aroma of Shandong matcha were identified using headspace solid-phase microextraction combined with gas chromatography mass spectrometry (HS-SPME-GC/MS) and gas chromatography mass spectrometry combined with olfaction (GC-O-MS). These volatile components include dimethyl sulfide (DMS), α-Ionone, hexanal, benzaldehyde, (E)-β-ionone, (E, E)-2,4-heptadienal, (Z)-2-penten-1-ol, 1-penten-3-ol, β-cyclocitral, 3-methyl butanal, Nonanal. Further aroma recombination and omission experiments reveal that DMS (P <
0.001), α-ionone (P <
0.001), hexanal (0.001 <
P <
0.01), benzaldehyde (0.001 <
P <
0.01), and (E)-β-ionone (0.01 <
P <
0.05) are key contributors to the seaweed fragrance, with DMS and α-Ionone being the main aroma components. This study identified the key aroma compounds of seaweed-like in Shandong matcha, explored the synergistic and antagonistic effects between these aroma components, and provided a theoretical basis for the quality control and scientific brewing of Shandong matcha.