The invention discloses an automatic bolt. The automatic bolt comprises a bolt box and a bolt rod movably penetrating through the bolt box; a lock hook is hinged to the outer side of the bolt box by use of a rotating shaft; the axis of the rotating shaft is perpendicular to the longitudinal axis of the bolt rod; a clamping hook part is arranged on one end of the lock hook; a first return spring is mounted on one end, far away from the clamping hook part, of the lock hook; the rotating shaft is located between the clamping hook part and the first return spring; a guide groove is formed in the bolt box; the clamping hook part of the lock hook extends into the guide groove; the clamping hook part is provided with a first guide surface and a first limiting surface; a limiting block is arranged on the bolt rod and provided with a second limiting surface; the second limiting surface can be matched with the first limiting surface so that the limiting block can be hooked by the clamping hook part; a second return spring, which can be squeezed by the matched limiting block and bolt box when the bolt rod is pushed, sleeves the bolt rod. The automatic bolt is simple in structure and durable; when the automatic bolt is used, a self-locking and unlocking function can be realized just by pressing the bolt rod or the lock hook; as a result, the automatic bolt is very convenient to use.