Understanding vegetation dynamics and their driving mechanisms is crucial for predicting ecosystem responses. In this paper, we present a 46,300-year pollen record from the Dahu swamp (eastern Nanling Mountains, south China), so far the longest high-resolution lacustrine sequence in the subtropical monsoon region, to reconstruct vegetation dynamics and decipher different drivers. Biomization and principal component analyses were used for quantitative reconstruction of vegetation evolution history since similar to 46.3 cal kyr BP. During Marine Isotope Stage (MIS) 3b (similar to 46.3-41.2 cal kyr BP), warm and humid climate promoted the expansion of evergreen broadleaved forests (EBLF). A transition to cooler and drier climates in MIS 3c (similar to 41.2-26.8 cal kyr BP) favored the prevailing of deciduous broadleaved forests (DBLF) and herbaceous taxa. The Last Glacial Maximum (LGM, similar to 26.8-17.4 cal kyr BP) of MIS 2 was featured by a mixed forest dominated by Fagus and Tsuga under cool-wet climate, sustained by weakened East Asia summer monsoon (EASM), persistent fog-cloud layers, and the topographic barrier effects of Nanling Mountains (NLM). Deglacial warming (similar to 17.4-12.2 cal kyr BP) triggered the expansion of thermophilic taxa (Cyclobalanopsis/Quercus (E)). The early Holocene (similar to 12.2-8.2 cal kyr BP) was marked by the dominance of EBLF under intensified EASM. Lake expansion and hygrophilous herbs prevailed during the mid-Holocene (similar to 8.2-4.2 cal kyr BP), whereas the late Holocene (similar to 4.2-0.6 cal kyr BP) was characterized by sparse vegetation cover (possibly open mosaic of forest and grassland), probably associated with cooling and intensified human activities especially since similar to 2.8 cal kyr BP. Spectral and wavelet analysis identifies orbital-scale precession-driven EASM variability (20.3-kyr cycle) since MIS 3b, modulated by tropical ocean-atmosphere oscillations (12.2-kyr cycle) and North Atlantic shifts (1.0-kyr cycles). By revealing how insolation-driven climate and topography together created cool, moist micro-refugia, the presence of Fagus and Tsuga forests during the LGM offers a basis for re-evaluating the hypothesis of extreme aridity in subtropical regions. This multi-scale analysis integrates orbital forcing, regional topography, and anthropogenic impacts, providing a framework for understanding subtropical forest resilience under climatic extremes.