Abstract: This study investigates the extreme compound cold-wet event in southern China during January–February 2024, which was the second most extreme event recorded since 1960. Two cold-wet processes occurred during this period. The first process, from 22 January to 23 January, exhibited a more intense cold surge, while the second, from 1 February to 7 February, featured more extreme precipitation and longer duration. This extreme cold-wet event was attributed to the combined effects of El Niño and positive North Atlantic Oscillation (NAO) in winter, coupled with intense convection in the western tropical Indian Ocean associated with a positive Indian Ocean Dipole (IOD) from the preceding autumn. El Niño and the Indian Ocean Basin mode in winter are conductive to enhanced anticyclone over the western North Pacific. Over the western tropical Indian Ocean, the enhanced convection associated with the warm sea surface temperature in winter and the positive IOD in preceding autumn can trigger an anomalous upper-level anticyclone over the Arabian Sea, enhancing the subtropical jet and deepening the India-Myanmar trough. The deepened India-Myanmar trough and the strengthened subtropical anticyclone over the western North Pacific enhance water vapor transport and subsequent extreme precipitation in southern China. Moreover, positive NAO and strengthened westerly jet stream induce widespread cooling in subtropical Eurasia, including southern China. Analysis from the backward trajectories using the HYSPLIT model confirms that moisture from the west and cold air from northern China at the near surface favored the compound cold-wet event in southern China. The extreme conditions of ENSO and NAO in winter and IOD in autumn jointly contributed to this extreme compound event.