Abstract: Na2SiO3/Al2O3 supported solid base catalyst was prepared by impregnation method and used as catalyst for synthesis of biodiesel from waste cooking oil and methanol. The effects of reaction conditions, such as mole ratio of methanol to waste cooking oil (M/O), catalyst dosage and reaction time, on the conversion were investigated. Finally, the optimum reaction conditions were obtained as follows: M/O mole ratio of 7.0, Na2SiO3/Al2O3 catalyst dosage of 9.0% (based on total mass of oil and methanol) and keeping at boiling state for 4 h; under such conditions the average conversion of waste cooking oil reached 95.3%.