A extraction method of silica comprises the steps of: mixing well-washed rice straw (or rice bran) and ethylene glycol containing 0.1-1% of acid so that the weight ratio may be 0.05-0.1, reacting at a constant temperature of 80-150 C and filtrating the mixture for pretreatment; diluting one of condensed enzymes derived from Phanerochaete chrysosporium, Polyporous adults, Myrothesiumverrucaria and Trichoderma reesei in acetate or citrate buffer making a composing solution of 6ncu ml; reacting the pretreated rice raw sample at 40-50 C for 2-6 hours in 100ml of the composing solution; oxidizing the filtrated sample completely at 400-500 C.
