Abstract: In order to determine effects of rib support on axial compression behaviors of composite stiffened panels, composite stiffened panels with I shape and hat shape cross-section without and with rib support were investigated experimentally and numerically. In axial compression tests, strain gauge and Moiré interferometry were used to monitor timely the buckling load and buckling modes of specimens, fracture section was observed aimed to analyze the fracture mechanism of structural damage. Based on the software of ABAQUS, a finite element model was developed to simulate the buckling and post-buckling progress of the stiffened panels, then the damage mechanism of stiffened panels was further analyzed by stress distribution evolution on the buckled antinode line and node line. The calculated results are coordinated with the testing results very well. The results indicate that the rib support has changed buckling mode but no impact on the buckling load for stiffened panels with different types of stiffener. The collapse load has a slight difference between with the rib support and without the support on the node line for the stiffened panels with I shape stringer, while that of the former panels has increased by 26.2% than the latter panels for the stiffened panels with hat shape stringer which the rib support was located on the antinode line. Stress distribution concentrates into interface between the stiffener and skin on the antinode line, high stress will induce interface debond, which will lead to collapse of structures concentrating on the antinode line.