The fatigue crack in bridge deck is one of the most important defects of steel box girder,which endangers the safety and service life of bridge. The cracks are classified according to their locations and propagation directions. The main causes of fatigue crack in bridge deck of steel box girders includes structure stress state,stress concentration effect,vehicle overload,manufacturing defects,etc. This paper puts forward several reparation methods by welding,such as gauging and repair welding directly,welding with backing,and welding after replacement of partial members. The applicability of different methods by considering the types of cracks,development degree of cracks,and the construction conditions of bridge site is discussed as well. And supplementary measures should be taken if necessary. The key points of detecting and locating of cracks,selection of welding procedures according to specific situations,and detail treatment are summarized. This paper can be the reference for the establishment of crack reparation methods in different situations.