The invention relates to a deep sea liquid sample releasing device, in particular to the device which can carry a liquid sample and then releases the liquid sample into sea water after reaching a designated depth according to an instruction, and belongs to the field of sea information detection. In the deep sea liquid sample releasing device, a sample tank is provided with a water inlet and a sample outlet and communicated with the sea water, so that all faces of a piston for pushing the sample are stressed under the equal pressure, and a pre-canned liquid sample cannot leak in the process of moving to the deep sea. The piston is pushed by the elasticity of a spring so as to release the liquid sample. When the device is used, the spring is stretched, then the liquid sample is canned, and a tail end of a steel wire rope is connected with the releasing device; the releasing device releases the steel wire rope according to the instruction after reaching the designated depth; and the liquid sample is pushed out through the piston under the action of the elasticity of the spring, and meanwhile, the sea water is absorbed from the water inlet so as to maintain the pressure balance in the sample tank.