In order to study the seismic performance of steel staggered truss system,a 1/3 scaled five-story structural model with composite truss was tested under quasi-static loading.Based on the test results,the failure mode was found,together with bearing capacity,ductility,stiffness,and energy absorbing ability,etc.,and following conclusions could be suggested:(1) The structural system had high bearing capacity and transverse rigidity,but low ductility;(2) The structural weakest story lied in ground floor for composite truss structure;(3) The diagonal members subjected to tension rupture or compression buckling,so their plastic deformation ability must be strictly limited,i.e.,the width-to-thick-ness of constituent plates should satisfy the seismic demand of brace in centric braced frame;(4) The failure mode of structure belonged to beam (truss) plastic hinge mechanism,large quantity of plastic hinges formed in truss before appeared in the column.