An anti-vibration anti-loosening threaded fastener is revealed. The threaded fastener includes a bolt and a nut. The bolt consists of a head, a stud disposed on a bottom surface of the head, and a through hole mounted axially in the stud. The nut is composed of a threaded slotted portion provided with an opening facing upward and fastened to the stud by threaded connection, and a post protruding from central area of a bottom of the threaded slotted portion. The post and the through hole are disposed eccentrically to each other so that forces that pull the bolt and the nut together are generated when the bolt and the nut are threaded and fastened with each other and the post is mounted into the through hole. Thereby the bolt and the nut are fastened more tightly and the threaded fastener is vibration resistant and anti-loosening.