Surface modification method for silicon dioxide

The invention provides a surface modification method for silicon dioxide. The method comprises the following steps: cleaning the surface of a silicon dioxide sample; continuously heating the silicon dioxide sample at 490-510 DEG C for 30-35 minutes; hydroxylating the surface of the silicon dioxide sample, namely putting the silicon dioxide sample into an electrolytic tank filled with 0.025-0.030%of a calcium chloride or magnesium chloride solution, and electrically exciting the surface of silicon dioxide by using 1.5-1.7 V/cm direct current to promote Si-O-Si bonds to break and combine with H and OH in water; and performing alkylation on the silicon dioxide sample, namely putting a silicon dioxide sample having undergone hydroxylation treatment by an electric excitation method intoa novel silane coupling agent reaction solution with a preferred ratio of KH560 to benzene to methanol to be 1: (9-11): (0.5-0.7), and completing an alkylation reaction to obtaining the surface-modified silicon dioxide sample.