Abstract: In the manufacturing procedure of composite single-lap joints，some mesostructures of ten form at the overlap ends. Because there are severe strain/stress concent rations at the overlap ends，these mesostructures may have effects on the mechanical performance of the joints. The effects of mesostructures at the overlap ends，including resin fillets and composite bulges，on the mechanical response of adhesively bonded laminated composite single-lap joints under tensile load were investigated by experimental measurement and finite element analysis. By digital image correlation technique，the strain distributions at the overlap end were measured. A nonlinear finite element analysis based on the submodel technique was executed to analyze the functions of the mesostructures at the overlap ends. The results from experimental measurement are in reasonable agreement with the finite element analysis. The results from experimental measurements and finite element analysis indicate that resin fillets at the overlap ends could carry a portion of load so that the strain/stress concent rations at the overlap ends are reduced. The functions of composite bulges are related to their own structures，so their effects are different for different composite bulges.