During 2016-2017, two typical plant litters (Spartina alterniflora (SA) and Cyperus malaccensis (CM)) in ecotone formed by SA invasion in Northwest Shanyutan of the Min River Estuary were studied. Furthermore, the effects of siltation by SA invasion on decomposition of and sulfur (S) release from different litters were determined by in situ decomposition experiment, which included three one-off siltation treatments[no siltation treatment (0 cm/a, S₀), current siltation treatment (5 cm/a, S₅), and strong siltation treatment (10 cm/a, S₁₀)]. The results showed that the decomposition rate of SA and CM litters significantly decreased with increase in siltation depth. Compared with that in the S₀ treatment, the decomposition rate in the S₅ and S₁₀ treatments decreased by 49.09% (SA) and 35.14% (CM), and 56.36% (SA) and 44.59% (CM), respectively. The content of TS in SA and CM litters generally increased with increase in siltation depth, but the values in CM litter increased by a large margin. The net release of S in SA and CM litters in different siltation treatments was observed throughout the decomposition process and the release amount generally decreased with increase in siltation depth. However, in the same siltation treatment, S release from SA was significantly higher than that from CM. The differences in decomposition rate and S release amount of the two litters in different siltation treatments depended not only on the sediment EC in decomposing environments, but also on the dry mass remaining, initial substrate quality (C/N and C/S), and variations in substrate quality caused by the alteration of nutrient conditions. We found that both the decomposition rate and S release from the two litters decreased with increase in siltation depth, but with the same siltation treatment, the decomposition rate and S release from CM were higher than those of SA.