Sedge (Carex riparia), is a weed and waste product of agriculture. After the use of the organic elements as fuels, the leavings including large amounts of silica can be used as economically viable raw material for the production of silica based products. The purpose of this study is obtained of pure silica form sedge and also synthesis of ordered nano porous silica with hexagonal structure, type MCM-41 with hydrothermal method by silica source that extracted from sedge. To attain high-purity of the silica, the optimization of the process conditions of the burning temperature, hydrochloric acid leaching treatment of sedge biomass and acidic reflux process of sedge ash were conducted to remove the metallic impurities such as K, Na, Ca, Mg, Fe, P, etc. X-ray diffraction studies of obtained silica reveal increasing peak width (amorphousity) with decreasing burning temperature. X-ray Fluorescence (XRF) results show that high purity amorphous silica materials with 91.13% were prepared from sedge by applying the 1N hydrochloric acid leaching, refluxing treatment and burning process at 600˚C in electronic furnace. The synthesized MCM-41 were characterized by X-ray diffraction (XRD), N2 physisorption measurements (BET), Fourier transform infrared (FT-IR) spectrometry and scanning electron microscopy (SEM). X-ray diffraction pattern of the resulting MCM-41 revealed typical pattern of 2d-hexagonal mesophase. The other experimental results revealed that the specific surface area was 778 m2/g, total pore volume was 0.745 cm3/g and average pore diameter was 3.78 nm.