Abstract: The compressional properties of composite single-stiffened panel specimens with rib were investigated through tests and finite element methods. Specimens with and without connector between stringer and rib were investigated. Test and numerical results reflect that specimens with connector between stringer and rib have higher rigidity, higher critical buckling loads, smaller deformation quantities in the post-buckling loading progress and smaller ultimate failure loads than specimen without connector. The ultimate failure mode of the specimen is always the interfacial debonding between stringer and panel, which reflects that the connector between stringer and rib has no effects on the final failure mode of the stiffened panel specimen. In the designing of composite airfoil structure, effects of connector between stringer and rib on the initial critical buckling load, post-buckling deformation and carrying capacity of the structure should be considered.