Automatic opening anchor device

The invention provides an automatic opening anchor device which comprises an anchor body, an anchor hook, an elastic torsion piece and a pressure adjusting piece, wherein an opening is formed in the anchor body, and an accommodating cavity connected with the opening is formed in the anchor body; the anchor hook is arranged in the anchor body and connected to the anchor body through a rotary connecting piece, and a limiting part is arranged on the anchor hook; the elastic torsion piece sleeves the rotary connecting piece, one end of the elastic torsion piece abuts against the limiting part, andthe other end of the elastic torsion piece abuts against the anchor body; the pressure adjusting piece is arranged in the accommodating cavity and connected with the wall of the accommodating cavityin a sealed mode, a sealed space is defined by the pressure adjusting piece and the accommodating cavity, and limiting structures which are matched with each other to limit rotation of the anchor hookare arranged between the p