Due to environmental impact, overuse and material defects and other factors, the structure will appear with the passage of time such as concrete carbonization, steel rust expansion, concrete defects and other diseases. These diseases have a great negative impact on structural durability. In order to ensure that the structure can work normally, it is necessary to take some strengthening measures. Taking the strengthening project of Yongjiang Bridge in Nanning City as the research background, this paper analyzes the causes of several diseases which have great influence on the durability of the structure, and introduces the working principle and construction technology of different strengthening technologies. The comprehensive strengthening technology used in the project mainly includes: brushing permeable concrete rust inhibitor, epoxy mortar or epoxy concrete to repair defects, pasting glass fiber cloth, painting anti-corrosion coating, etc.