The invention provides an 
underwater depth-setting releasing device, which comprises a base, an upper cover, a 
piston, a leather bag and a rupture disk. The 
barrel bottom of the upper cover is provided with a through hole, glycerin is filled in the leather bag, the 
piston and the leather bag are placed in the upper cover, the rupture disk is clamped between the base and the upper cover which are fastened by a bolt, the side wall of the upper cover close to the 
barrel bottom is provided with a 
steel ball hole, a bearing sleeve is sleeved outside the upper cover and provided with a 
steel ball hole corresponding to the 
steel ball hole on the side wall of the upper cover, steel balls are arranged in the steel ball holes, the bearing sleeve is provided with a steel ball 
retainer ring, and a 
ballast is connected to the base. The 
underwater depth-setting releasing device has the advantages of relatively low cost, large bearing load, light weight, small volume, simple installation, easy detection and control, high control accuracy and the like, can be applicable and practicable in a predetermined 
ocean depth, and can be applied to an 
underwater robot, an underwater construction 
machine and underwater equipment.