Abstract: Due to the limitation of jack-up rig operational characteristics, underwater structure inspection and repair are often needed during the operation service at well position. How to complete this kind of work quickly, economically and safely is an engineering problem that the offshore petroleum industry is faced with. In this paper, aiming at providing a solution for underwater inspection and repair problem of the jack-up rig, an offshore operation technique of “jack-up at well position, lifting leg alternately” is put forward, which can satisfactorily solve the problem of underwater survey in lieu of dry-dock survey of the jack-up rig and underwater structure repair during operation service at well position.