The invention discloses a bolt and nut fastener. The fastener comprises a nylon bolt and a nylon nut, the nylon bolt comprises a rod part and a head part arranged at one end of the rod part, a separating groove is formed in the middle of the rod part, and the separating groove divides the rod part into two mutually symmetric clamping blocks; a separating piece is inserted into the middle of the separating groove, the two side surfaces of the separating piece are correspondingly attached to the inner walls of the clamping blocks, and the height of the separating piece is larger than the heightof each clamping block; a plurality of teeth A are arranged on the outer side surfaces of the clamping blocks, the cross sections of the teeth A are in a triangular shape, the top surfaces of the teeth A are inclined planes, and the bottom surfaces of the teeth A are horizontal planes; and a mounting hole is formed in the nylon nut, a plurality of teeth B matched with the teeth A are horizontallyand annularly arranged on the inner side surface of the mounting hole, the cross sections of the teeth B are in a triangular shape, the top surfaces of the teeth B are horizontal planes, and the bottom surfaces of the teeth B are inclined planes. The bolt and nut fastener is convenient to mount and can effectively prevent looseness from occurring during cooperating between the bolt and the nut.