Abstract: This paper recommands the design method of Dandong Shahe large bridge and the calculation results. The dynamic analyses of the large-spanned arch bridge and the related problems of the earthquake-proof construction design is explicated.We have the following views:1. Because of the curvature of the arch axis and the effect of the elastic compression, the effect of the vibration couplings of the orthogonal directions in the arch plane is very obvious. 2.When the earthquake sets on the arch plane,there will be considerable strain on the lower edges of the arch springings. This is in agreement with the damage phenomenon of the arch axis. Large stress and strain may occur from L/4 to the arch crown. 3. When the earthquake acts outside the arch plane, a very large horizontal displacement and torsional moment will occur in tee arch rib. In Tongshan earthquake two lower bearing tyqe arch bridges collapsed. This was the consequence of the horizontal earthquake action. 4. The effect of the vertical earthquake component is quite big. It should not be neglected in the earthquake-proof construction design. 5. The maximum type parameters and coefficients may occur in the higher-order vibration type, therefore, if we merely make computations for the earthquake-proof construction design of the large-spanned arch bridge of the first vibration type, it may not be safe and sound. 6. There is the apparent effect of the earthquake hypogene to the arch bridge earthquake by the frequency spectrum of the earthquake wave. Therefore, we consider that it is apt to proceed the overall computations for the aseisma tic constructions by means of the dynamic analysis in dealing with the large-spanned arch bridge.