The invention relates to an ejection type unlocking mechanism for a deep sea cableless sampling device. The ejection type unlocking mechanism comprises an inner tube and an outer tube. The outer wall of the outer tube is fixedly provided with a circumferential boss at the top, sleeved with an unlocking sleeve in the middle and provided with a trigger device at the lower part, at least two locking through holes are uniformly formed in the middle section of the tube wall of the outer tube in the circumferential direction, locking grooves are formed in the outer wall of the inner tube in the circumferential direction, the locking through holes in the outer tube and the locking grooves in the inner tube are in abut joint to form spaces, each space is provided with a locking bead used for locking the relative positions of the inner tube and the outer tube, bead unloading grooves capable of accommodating the entire locking bead are formed in the inner wall of the middle of the unlocking sleeve in the circumferential direction, the trigger device is provided with a trigger ring at the bottom and provided with a push pipe capable of being in contact with the unlocking sleeve, the trigger ring and the push pipe are fixedly connected through a connecting rod, when the locking beads lock the positions of the inner tube and the outer tube, the locking beads are locked by the inner wall of the unlocking sleeve above the bead unloading grooves, as well as the locking through holes in the outer tube and the locking grooves in the inner tube, the bead unloading grooves are positioned below the locking beads, and the distance between the upper end of the unlocking sleeve and the lower edge of the circumferential boss is greater than the distance between the bead unloading grooves and the locking beads. The unlocking mechanism can be used for unlocking and recovery of submarine detection equipment, triggering is stable, unlocking is smooth, and the success rate of releasing is high.