In view of the problem that the structural safety risk is caused by the serious corrosion at the lower chord of steel approach bridge of Qingdao Port phase I oil-wharf,we study the design of temporary strengthen,apply the strengthen method of load shedding with pre-stress to the steel strand of lower chord,ensure the structural safety in the process of comprehensive strengthen,and form the strengthening technology of unload steel truss bridge.The key technology includes the arrangement plan of steel strand,end anchorage,steering block and damping measure etc.The results show that the strengthen technology has the advantages of light-load and high-speed,which can be used for temporary structure and permanent stressed member.This technology can provide the references for the similar projects.