In order to establish an efficient and accurate procedure for the vertical seismic performance evaluation of space truss structures,a modal pushover load pattern,taking the structural mass distribution into consideration,was adopted so as to modify the establishing process of the equivalent single-degree-of-freedom (ESDF) systems based on the overall structural stiffness parameter. The characteristic of the vertical vibration of space truss was investigated,which is influenced by gravity and obviously asymmetric. By assuming the equivalent load-deformation relationship of the ESDF system to be “one-side” elastic,the simplified modal ESDF systems for space truss structures were established. Basic processes for both vertical seismic response analysis and vertical seismic performance evaluation of space trusses were given. It is demonstrated by a numerical example that the proposed equivalent-simplified-model-based procedure can yield accurate vertical displacement response (error of central nodal displacement is less than 5%) and can approximately locate the inelastic members of space truss structures. Meanwhile,the time consuming of the proposed simplified procedure is much less than that of the nonlinear response history analysis. Moreover,for practical engineers,the proposed approach is pretty concise and easy to use.