the present invention belongs to the field of surface modification of solid materials , specifically relates to a method of changing the surface wettability of polymer materials . the method of the present invention comprises of rubbing the surface of the polymer materials various times by using sand paper of different grades with a determined pressure at the ambient temperature , so as to change the contact angle of said surface of polymer material with water thereby changing the surface wettability of the polymer materials to different degrees . the method of the present invention has advantages of using devices that are simple , low cost , and the surface characteristics of the polymer materials could be changed from hydrophilicity to hydrophobicity , from hydrophobicity to super hydrophobicity , or from hydrophilicity to super hydrophilicity , at ambient temperature without any special requirement to the polymer materials or the preparation process thereof .