The invention discloses a small-sized contact and an ultramicro rectangular electric connector using the same, the small-sized contact comprises a plug and a socket matched with the plug, the plug comprises a head-containing shell, a pin insulator, a toothed spring contact pin, a hexagon socket bolt, a fixing ring, a connecting cable and a first black resin adhesive, and the plug comprises a plug-containing shell, a pin insulator, a toothed spring contact pin, a hexagon socket bolt, a fixing ring, a connecting cable and a first black resin adhesive; a first black resin adhesive used for protection is fixedly installed at the bottom of the inner end face of the head-containing shell, connecting cables used for connection are evenly and fixedly connected to the inner end face of the first black resin adhesive at equal intervals, and fixing rings are symmetrically and rotationally clamped to the inner end face of the head-containing shell. And an inner hexagon bolt is rotationally clamped on the inner end surface of the head-containing shell through a fixing ring. The invention has the advantages of high density, light weight, miniaturization and miniaturization, can tolerate harsh use environments such as strong vibration and impact, is particularly suitable for application occasions with special requirements on use space and equipment light weight, adopts screw type locking, and is quick to assemble and disassemble and reliable in locking.