Abstract: The implicit dynamic analysis by finite-element (FE) software ABAQUS was utilized to conduct numerical simulations on the demolition and collapse process of three common plane truss structures, namely, orthogonal, orthogonal diagonal, and three-dimensional space trusses, and four pyramid space trusses, i.e., one-way folding line, square pyramid, diagonal square pyramid, and triangular pyramid space trusses. The collapse test of the plane truss structure and the actual demolition and collapse situation of the roof space truss of Shenzhen Gymnasium were compared with the numerical simulations, which verified the accuracy of the numerical simulation. The sensitivity analysis of elements was made to calculate the importance factor of elements and determine the important elements in the demolition of different space trusses, and corresponding demolition plans were formulated. The research results show that after the fixed element group at the column ends of space truss structures is demolished, the compressive stress of the residual elements at the column ends is increased, and buckling instability caused by the compressive stress accounts for the large vertical deformation of the space truss. When the space truss falls down below the top of the column, the elements at the column ends are subjected to the tensile stress, and the catenary action in the truss provides an alternate way for the vertical load, which leads to the strength failure, the main reason for the overall collapse of the space truss.