Damper with good sealing performance

The utility model discloses a damper with good sealing performance in the technical field of dampers, which comprises an outer pipe and a piston rod arranged in the outer pipe, the piston rod is inserted in a front sealing structure, the front sealing structure is arranged at the front end of the outer pipe and used for sealing the outer pipe, and the piston rod is arranged in the outer pipe. The front sealing structure sequentially comprises a check ring, a sealing ring and a front end cover from inside to outside, the check ring comprises an extension ring and a first convex ring, the extension ring extends towards the front end cover, a containing cavity for containing the sealing ring is formed in the extension ring, the sealing ring is connected into the containing cavity in a sliding mode, and the first convex ring is arranged in the containing cavity. The front end cover is in threaded connection with the outer pipe through an external thread, a containing groove is formed in the side face, close to th