Large-span spatial structures are sensitive to spatially non-uniform seismic excitation (such as traveling wave effects). To gain a deeper understanding of their dynamic response mechanisms and assess the influence of key structural parameters, a refined finite element model validated through on-site modal testing was established using a curved steel tube truss structure with a span of 67.5 m in Leshan City, Sichuan Province, as the research subject. By comprehensively applying modal analysis, response spectrum analysis, and elastic time history analysis methods, the study systematically compared the dynamic characteristics, displacement, and internal force responses of the structure under consistent input and traveling wave input conditions, and quantitatively analyzed the sensitivity of the lower chord member cross-section parameters. The research results indicate: (1)The traveling wave effect significantly alters the response distribution, exacerbating the non-uniformity of displacement and internal forces, resulting in significantly increased peak displacements and internal forces at critical locations such as the arch crown, tower top, and tower base compared to consistent excitation; (2)A 10% reduction in the lower chord diameter increases mid-span deflection by 15.2% and exacerbates stress concentration, with this effect being significantly greater than that of wall thickness adjustments; (3)Traveling wave input induces significant time delay and amplitude amplification effects, which become more pronounced as long-period components strengthen. This study elucidates the response patterns of large-span curved trusses under non-uniform excitation and the control role of key components, providing a basis and parameter control strategies for seismic design of similar structures.