Abstract: The scaled one-span bridge model of a six-span Reinforced Concrete Arch Bridge that has been in service for more than 30 years was fabricated using organic glass.Considering the different constraint conditions of continuous and segmental decks,static and dynamic tests were performed respectively in laboratory.The effects of the constraint condition on the mechanical property of the bridge are discussed.It is shown that the constraint of the deck has a significant effect on the structural stiffness(the stronger the constraint,the higher the structural frequency).It is indicated that the horizontal dynamic characteristic is more sensitive to the constraint of the deck than the vertical dynamic characteristic,and the constraint condition in the middle of the deck has a great effect on the structural frequency.The variation tendency of the static mechanical property with the constraint of the bridge deck is also obtained.Comparing with the field monitoring data,the reliable bridge model that can well reflect the actual mechanical properties of the original structural is obtained.