The tendency of deep water and offshore wharf construction leads to the enlargement of the upper precast beam slab.However,due to severe offshore conditions,the installation process by conventional rigging boat is insufficient in ensuring accuracy.Taking Dongjiagang 400 000 ton class mining wharf of Qingdao port for example,we introduce a complete set of accurate installation process for 500 t precast box girder at offshore,which mainly includes a combination adoption of offshore tower crane,3-D jack and beam-adjustment lever.