Huguangyan Maar Lake (HML) has long been recognized as a critical repository for reconstructing paleoenvironmental changes in southern China. However, interpretations regarding the dynamics of the Asian monsoon system derived from this site have been diverse and, at times, contradictory. To better understand the sediment source-to-sink processes and associated magnetic characteristics, this study investigates grain-size distributions and rock magnetic properties based on 56 lake surface sediments collected from varying water depths, as well as 23 topsoil and 4 volcanic rock samples obtained from the HML catchment. Our findings reveal that the lake sediments are predominantly sourced from the surrounding catchment and transported into the lake via surface runoff. Grain size generally decreases toward the center of the lake and is strongly influenced by water depth. Nevertheless, the relationship between grain-size and water depth is complex, with a threshold depth of approximately 5 meters marking the effective limit of wave-induced sediment reworking. Magnetic minerals in the lake sediments are primarily composed of stable single-domain and superparamagnetic magnetite, resembling those found in local topsoil and volcanic rocks but differing from the magnetic signature of aeolian dust transported by the winter monsoon. The concentration of magnetic minerals is largely source-dependent, with higher values observed near magnetite-rich coastal zones. Additionally, water depth exerts a notable influence on magnetic concentration, likely due to greater transport distance from source areas and the partial dissolution of magnetic particles under suboxic to anoxic conditions within the lake. The magnetic record preserved in HML sediments may reflect variations in the intensity of the Asian summer monsoon, which controls the supply of weathered material from the catchment, the accumulation of organic matter, and overall water depth.