The present invention relates to a tractor mower with improved cutting and shredding performance, and a method for cutting and cutting the vegetation using the weed, by providing a chain on the rotating shaft of the mower to rotate and entangle it by increasing cutting and shredding power for vegetation to be cut. A chain member 10 connected to the rim of the rotating plate 15 fixed to the end of the gear center shaft 17 connected to the gear in the gear box 12 so that the surrounding vegetation can be neatly organized up to the root; The chain member 10 is formed in the form of a chain having a length, and is provided with at least two or more and positioned parallel to the ground when rotating, and the horizontal unit at the end side of the chain member 10 coupled to the rotating plate 15 (10a) is seated on the upper side of the rotating plate 15, the one-step fixing member 63 is formed on the upper side of the rotating plate 15 is formed with a release preventing groove 64 surrounding the outer side of the horizontal unit 10a The two-stage fixing member 61 which is provided in close contact and covers the upper side of the horizontal unit 10a located in the departure-preventing groove 64 on the upper side of the one-stage fixing member 63 is provided in close contact, and the chain member Chain safety cover (20) is provided spaced apart from the top of the (10) to protect the upper side of the chain member (10); The chain safety cover 20 is formed to be wider than the rotational radius of the chain member 10 to protect the upper side of the chain member 10, and the top plate cover part based on the traveling direction of the mower Consists of both side protection blades (23) that are bent downwardly extending to both sides of the (22), inflow of the open vegetation between the side protection blades (23) of the front side on the basis of the moving direction of the mower A portion 11 is formed, and the rear vegetation discharge portion 21 in an open form is forme