Large span spatial steel structures, such as gymnasiums, exhibition halls, airport terminals, or railway hubs, have developed rapidly over the last four decades. However, the mechanical properties of these structures under complex loads, particularly their seismic performance under severe earthquakes, are not sufficiently understood. During the 2013 M7.0 Lushan earthquake in China, some of the large span spatial structures suffered damage of varying degrees, which necessitates a review of previous seismic designs and theories. This paper investigates the characteristics and rules of the seismic damage of large span spatial structure during the Lushan earthquake and discusses the possible causes of such damage. A shaking table test was conducted with a down-scaled model of a double-layer cylindrical shell structure to obtain the dynamic response of a structure by reasonably arranging the acceleration, velocity and displacement measuring points. The failure pattern and progressive collapse process of the structure under a severe earthquake were investigated. The buckling of members increased with the increment of ground motion, although this effect was not considered in the present code for seismic design for double-layer shell spatial structures. The seismic damage in the test was mainly represented by overall buckling of the upper chord, web member and lower chord, which is the direct reason for the structural collapse during a severe earthquake. The test results indicated that the change in surface curvature of the structure resulting from deformation during a severe earthquake transformed gravitational potential energy into kinetic energy and caused chord members to impact and fracture, thereby inducing progressive collapse of the structure. The findings of this paper provide a basis for the seismic theory and design of large span spatial steel structures. The buckling effect of double-layer cylindrical shell structures, the dynamic amplification effect of the support structures, and the transformation of gravitational potential energy to kinetic energy in particular would be of interest to researchers and designers.