In recent years, the rapid growth of the number of private cars has greatly increased the traffc pressure, so the quality of roads and bridges should be further improved. The paper expounds the related matters of road and bridge engineering from three aspects. Firstly, it expounds the construction principles of road and bridge engineering, which are regarded as the theoretical basis of follow-up research. Secondly, it analyzes the common diseases of road and bridge engineering, including bridgehead damage, reinforcement corrosion, and subgrade uneven settlement, etc. Finally, it puts forward the construction treatment technology of road and bridge engineering on the basis of the construction principles and taking the common diseases as reference.