The invention discloses a tool for forming traumatic surface at the edge of patency foramen ovale. The tool comprises a catheter, a guidepost, a supporting rod, a knife, an operation mechanism and a guide wire, wherein the guidepost is arranged in the catheter in a sliding mode; the supporting rod is arranged in a third guide hole of the guidepost in a sliding mode, and a supporting head is arranged at the front end of the supporting rod; the guidepost is connected to the tail of the knife in a pin joint mode, and a tool bit is arranged on the head of the knife; the operation mechanism comprises an upper drawing wire and a lower drawing wire, the knife is connected to one end of the upper drawing wire and one end of the lower drawing wire, the other end of the upper drawing wire penetrates through a second guide hole of the guidepost and extends outward, and the other end of the lower drawing wire penetrates through a first guide hole of the guidepost and extends outward; the guidepost is connected to one end of the guide wire, and the other end of the guide wire extends outward along the catheter. The tool is flexible in using, convenient to operate and small in trauma.