A ratchet buckle has a body and a trigger. One end of the body has two opposite pivotal holes, two opposite positioning notches, and a pivotal shaft penetrating the pivotal holes. Two ends of the pivotal shaft each have a ratchet wheel synchronously rotating with the pivotal shaft. One end of the trigger has two opposite shaft holes engaged to the pivotal shaft of the body and has a positioning rod transversally mounted on the trigger to engage the two positioning notches of the body. By operating the trigger to set the pivotal shaft free, the pivotal shaft is easily rotated to reel a strap.