The dynamic characteristic of space beam string structure was investigated in this paper. The modal analysis was firstly carried out with this structure and the corresponding upper single-layer shell without the lower cable-strut system. Then the time history analysis were performed to study the dynamic behavior of space beam string structures under earthquake action, including the effect of numbers of struts, sag-span ratios, stiffness of upper beams, prestress and area of cables. The results show that the lower cable-strut system does increase the stiffness of space beam string structures, and most vibration modes of the structure are vertical modes. The increase of numbers of struts, sag-span ratios and sections of upper beams are conducive to increase of structural stiffness and resisting global deformation. But the effect of prestress and area of lower cables on the seismic performance of space beam string structure is slightly.
