Autumn is a critical period during which the Antarctic waters transitions from melting to freezing; however, studies on organic carbon cycling in this season are scarce. This study investigated the concentrations and optical properties of dissolved organic carbon (DOC) in Prydz Bay during autumn. The results showed a significant negative correlation between CDOM and salinity in the upper water, indicating that the elevated CDOM in the upper water is mainly attributable to enhanced algal productivity, which is linked to freshwater input. Compared with summer, both DOC and CDOM concentrations in the upper water and density shelf water (DSW) were lower. Further analysis indicated that CDOM absorption at longer wavelength (325 nm) decreased more than that at shorter wavelength (254nm), suggesting that algae-derived DOC (with longer-wavelength absorption) is relatively labile, whereas the DOM that accumulates in autumn is more microbially derived.