The micrometer-scaled channels with different width and depth on the Si surface were prepared by femtosecond laser ablation. The relationship between the hydrophobicity and flow drag reduction has been studied through the measurement of water contact angle (WCA) and rheological characteristic experiment after the samples were made hydrophobic through a chemical reaction with an organosilane. It is found in the experiment that the bigger the WCA or the more hydrophobic water is, the more remarkable the effects of drag reduction would be. Accordingly, the certain-extent-controllable hydrophobicity of solid surface could be prepared by the laser ablation and also the characteristics of drag reduction would be controlled. 