Abstract: To investigate the characteristics of boundary layer turbulence and its variation mechanisms under the complex sea-land transition surface during a typhoon, this study utilized high-resolution WRF simulations of Typhoon “In-Fa” that impacted the Zhoushan Archipelago from July 24 to 25, 2021. Based on the comparison between the simulated results and observed data, the characteristics of turbulent kinetic energy (TKE) transport before and after landfall were analyzed, and the TKE budget equation was used to further explore the TKE budget characteristics. The results indicate that: (1) TKE exhibits a co-phase variation with wind speed and precipitation during different stages, including the influence of the outer spiral rainbands, the control of the eyewall rainbands before landfall, the relatively calm stage in the eye, and the recovery stage of the rear rainbands and circulation. (2) The sea-land transition terrain causes significant vertical fluctuations in TKE, with values on the islands significantly higher than in the surrounding sea, especially on the windward slopes, where TKE can exceed 20 m2/s2. After the typhoon moves out, TKE weakens over the islands, while it intensifies over the sea. (3) TKE variations are primarily influenced by wind shear, with wind shear and surface roughness differences enhancing TKE generation and transport, while the buoyancy term has a limited contribution. Prior to landfall, enhanced pressure gradients induced shear, promoting TKE generation and triggering strong convective precipitation. After the typhoon"s exit, the pressure gradient is re-established, and wind speed and precipitation intensify, with the roughness differences between the islands and surrounding sea modulating local wind shear. The findings provide theoretical support for typhoon disaster prevention and meteorological services for the Zhoushan Archipelago and other high-risk regions along the southeastern coast of China.