| Swamp forage is an alternative feed for ruminants due to as a source of nutrients and phytochemicals (tannins and saponins), including water mimosa, giant molests, and water chestnuts. The objective of this study was to evaluate the effect of swamp forages combination in the ration on the characteristics of rumen fermentability and methane production. The design used was completely randomized design (CRD) with 4 treatments and 4 replications. The treatments given were A (guinea grass and concentrate, 7:3), B (guinea grass, water mimosa and concentrate, 4:3:3), C (guinea grass, giant molest and concentrate, 4:3:3), D (guinea grass, water chestnut, and concentrate, 4:3:3). The value of dry matter digestibility (DMD), organic matter digestibility (OMD), pH, N-Ammonia (N-NH3), total volatile fatty acids (TVFA), partial VFA, and methane production, total bacteria, and protozoa were the variables observed. The results showed that the combination of swamp forage could increase (p<0.05) DMD, OMD, TVFA, partial VFA, and total bacteria, while N-NH3, methane production, and protozoa decreased. It was concluded that the combination of water mimosa in the ration was the best composition in increasing DMD, OMD, total bacteria, and rumen fermentability and reducing methane production.