The surface of the glass channel of microfluidic chip is treated with dichlorodimethylsilan. After the treatment, the silicon hydroxyl on the surface of the glass channel is silylated, which results in the reduction or even the elimination of the electroosmotic flow. Furthermore, full-potential linear-muffin-tin-orbital molecular dynamics method is used to investigate the micro -mechanism of surface reaction theoretically. The calculation results indicate that the hydrogen atom in silicon hydroxyl binds with the chlorine atom in dichlorodimethylsilan to form a stable HCl molecule and goes off, thereby the surface of the channel is covered with silylane.