The invention discloses a releasing tool which comprises a joint, a core tube, a spring, a jacking sleeve, a connecting barrel, clamping tile, a sealing device, a guiding shoe, a parent lock ring, a limiting barrel and a sealing barrel. A first end of the core tube is hermetically and fixedly connected with the joint, the connecting barrel sleeving outside the core tube is fixedly connected with the joint, an annulus is formed between the connecting barrel and the core tube, the spring, the jacking sleeve, the clamping tile and the sealing device are sequentially sleeved on the core tube, the clamping tile can axially slide along the core tube, is provided with a left-hand sawtooth external thread, and is divided into multiple portions circumferentially, the end portion of the clamping tile is provided with an inner bevel, the core tube is provided with a bevel boss corresponding to the inner bevel, a first boss is arranged on the core tube, the inner surface of the clamping tile is provided with a second boss corresponding to the first boss, the sealing device used for sealing between the core tube and the sealing barrel is sleeved at a second end of the core tube, the second end of the core tube is connected with the guiding shoe, the parent lock ring is arranged in the limiting barrel and can axially slide, the sealing barrel and the limiting barrel are fixedly connected, and the parent lock ring is provided with a left-hand sawtooth internal thread. The releasing tool is easy to assemble and operate.