Abstract: A finite element method was developed for the numerical analysis of advanced grid stiffened st ructure(AGS) , and the stability problem of AGS with an embedded delamination was investigated. Based on the Mindlinfirst-order shear deformation theory , a composite laminates element and a beam element were adopted to model theskin and the stiffener , respectively. The corresponding formulae for finite element analysis were deduced. By coordinate t ransformation and the geomet ry continuum condition of the skin and the stiffener , the element stiffness mat rices and geomet rical stiffness mat rices for the AGS were deduced. The governing equation for the stability problem ofthe composite grid stiffened plate and shell was established. The effect s of configuration , size , and location of thedelamination , and the height , the width , the dist ribution of the stiffeners on the stability characteristics of the AGSsubjected to a compressive load are discussed. The numerical investigation indicates that the buckling behavior of theAGS is much more complicated. The buckling load and modes relate to the configuration , size , and location of thedelamination , and the height , the width , the dist ribution of the stiffeners closely.