A screw post is detachably screwed with a self-tapping screw. The screw post includes a post body and a rib structure. The post body has an approximately triangular hollow structure formed therein. The approximately triangular hollow structure has three arc-shaped sides. The rib structure protrudes from an outer surface of the post body corresponding to at least one of the three arc-shaped sides in an axially-extending manner. The self-tapping screw is screwed into the approximately triangular hollow structure.