The damage extents identification of members in space truss is an important part in health detection of space trusses. It plays a decisive role for the safety and applicability of truss structure. Based on the location of members damage, through experiment and simulation method, the analysis method of use transient dynamic response for the study about the damage extents identification of members in four pyramid space truss is put forward. The displacement-time history curve is educed about the different damage extents of members' node, and the curve-fitting analysis is made using Matlab. It shows that the displacement-time history curve of members' node can approximate synthesis of linear in different damage extents. Through the analysis abut slope of the line and the damage extents of members, it can educe the relation about the slope value, displacement-time history curve about top chord, bottom chord, wed member both ends of the node, and the damage extents of members. It can accurately identified the damage extents of four pyramid space truss members by the relation, which can be referenced in the damage extents identification of members in truss structure of practical engineering projects.