<p>Based on simulations using the Regional Ocean Modeling System, this study investigates the impact of two sequential Typhoons Nesat and Nalgae (2011) on the subsurface thermal structure (30–150 m) of the northern South China Sea. Our findings indicate significant subsurface cooling along and on both sides of the typhoon track, with the most pronounced temperature decreases occurring to the right. The largest heat changes were observed during the first near-inertial period after the passage of each typhoon, with the overall heat loss induced by both being roughly comparable. The two typhoons, however, influenced the subsurface layer through distinct mechanisms. Typhoon Nesat induced strong vertical mixing that began to regulate the subsurface layer even prior to its arrival, primarily causing subsurface warming—an effect that dissipated rapidly after the typhoon passed. The intensity of this mixing was strongest along the track, weaker to the right, and weakest to the left. In contrast, Typhoon Nalgae did not generate marked vertical mixing. Both typhoons triggered strong vertical advection, which led to subsurface cooling and served as the dominant control on subsurface temperature changes. The intensity of vertical advection showed minimal variation along the track and on either side. Due to the preconditioning by Typhoon Nesat and the combined influence of the two typhoons, vertical advection was more pronounced during the passage of Nalgae and persisted after the typhoons had passed. Although horizontal advection was relatively weak, it contributed to subsurface warming during the post-typhoon recovery phase, whereas the effect of horizontal mixing was negligible.</p>