This study investigated the composition and phase of major biomasses fly ash in Thailand at different sintering temperatures by X-rays fluorescence spoctrometer (XRF and X-Rays Diffractometer XRD). All biomasses were sintered at different temperature (400 °C, 600 ํC 800 °C, and 1,000 "C) under same condition The result found that Rice husk ash, sugarcane leaves ash, Straw ash and Plam petiole ash at all sintering temperatures and Bagasse ash at 800 and 1,000 Chave silica content of 50 wt.%. The main phase of Rice husk ash, sugarcane leaves ash, straw ash, Plam petiole and Bagasse ash was found to be Sio, form. Theses result indicate that Rice busk asb, Sugarcane leaves ash, Strap ash. Paim petiole ash and Bagasse ash may be use substituted or additive for a silica source in tbe glass manufacturing process.