This invention relates to a wrench, especially a ratchet wheel wrench. The ratchet wheel wrench includes a wrench head on which a ratchet wheel groove and a crescent groove communicating the ratchet wheel groove are attached, a ratchet wheel is disposed in the ratchet wheel groove, a ratchet tooth support is disposed at one side of in the crescent groove, a spring is disposed at one end of the ratchet tooth support; a reed is disposed at the side in the crescent groove opposite the ratchet tooth support, one end of the reed is mounted in the crescent groove along the inner wall of the crescent groove, a protuberance is disposed at the other side of the reed, the protuberance is disposed in the spring.