Mangrove forest is one of the forests with high biomass storage in the tropics besides mainland forests. The mangrove ecosystem has an ecological function as a carbon reducer through a sequestration process (C-sequestration). One technique that can be used to calculate biomass is the use of remote sensing technology using satellite imagery and the application of transformation of the vegetation index. This study aims to obtain the best biomass equation model from several vegetation indices, analyze the estimated biomass value from Landsat 8 imagery in 2022, and map the distribution of the estimated distribution of average above-ground biomass of mangrove forest in Panai Hilir using Landsat 7 imagery and Landsat 8 in 2002 and 2022. This study used a systematic sampling method with a random start with 70 plots. Biomass calculations are carried out using allometric equations. Modeling uses the dependent variable (biomass) and the independent variable (vegetation index). The vegetation indices used are NDVI, GNDVI, and TDVI. The results of this study showed that the chosen equation model was the GNDVI (Green Normalized Difference Vegetation Index) linear equation model y = 11, 479x – 2,5569 with r2 of 0,404. The average distribution of above-ground biomass of mangrove vegetation at research sites 2002 was 109,66 tons/ha, with the highest biomass distribution being 200,48 tons/ha. The average above-ground biomass content of mangrove vegetation at the research location in 2022 is 98,28 tons/ha, with the highest biomass distribution of 213,10 tons/ha. In calculations using the selected model and index, in 2022, a total estimated average biomass was obtained of 405,52 tons/ha.