Abstract: A steel factory building has been used for over forty years and the crane system was damaged seriously.The renovation of the factory leads to raising the carrying capacity of the crane and their girders.The crane system was inspected and dynamic test was performed on the crane girders to obtain their deflection and stress.The load bearing capacities and deflection of the steel crane girders were calculated.Based on the inspection,dynamic test in site and calculation results,reinforcement measures for the crane system were proposed.Two strengthening methods of the steel crane girders by adding steel truss and I-shaped steel beam underneath the existing girders were presented.