Research by title the effect inundation period to summed dominant ratio (SDR) and biomass rice weeds of method SRI (system of rice intensification) in Indonesia. Research have been conducted in the Faculty of Agricultural Land Andalas University, Limau Manih, Padang, from February to May 2018. The study aims to identify noxious weed found in SRI method of paddy cultivation in Indonesia. Weeds that have summed Dominance Ratio (SDR) and the highest biomass in this study is a weed Cyperus rotundus, Scirpus juncoides Roxb., Fimbristylis miliacea (L.) Vahl, Cyperus pedunculatus and Richardia brasiliensis Gomez. Highest weed biomass obtained in the treatment of inundation 3 days old and weed biomass lowest is 15 days long inundation.