The invention relates to a ratchet chain stopper, which comprises a guide pipe, a chain stopper base, and a ratchet. The chain stopper base horizontally sleeves the guide pipe, the ratchet is connected to the chain stopper base in a pin joint mode, wherein a first trunnion and a second trunnion are arranged symmetrically on the two opposite sides of the chain stopper base, a first shaft sleeve anda second shaft sleeve respectively and tightly sleeve the outer parts of the first trunnion and the second trunnion, a first sliding bearing and a second sliding bearing are respectively sleeve the first shaft sleeve and the second shaft sleeve, and the outer parts of the first sliding bearing and the second sliding bearing are respectively connected with a buoy main structure and assembled withfixing chain stopper saddle for locking. According to the ratchet chain stopper, during an anchor chain pulled up through the guide pipe, upward rotation of the ratchet can be smooth, damage of the chain stopper to a floating body structure is avoided, and connection safety between the chain stopper and the floating body structure is improved; furthermore, when the anchor chain is lowered downward, the ratchet can further drop onto the chain stopper base with the anchor chain, and thus the ratchet can automatically fix and limit.