The utility model discloses a cross shaft universal joint self-locking sealing structure, which comprises a sealing cover and an end cover, wherein the sealing cover is a petal shape which consists of a plurality of steel plates, and the sealing cover is fixed in an end cover reserved hole. The dropping phenomenon of the sealing cover caused by the vibration when a cross shaft universal joint works can be avoided, the sealing performance of the cross shaft universal joint can be improved, long-term non-replacement of the sealing cover can be realized, the repair expense can be saved, and the service life of the cross shaft universal joint can be prolonged.