In order to study the buckling behavior and post-buckling behavior of stiffened panels with different opening sizes in aircraft structures under compression load， the corresponding test method and test fixture are designed and the compression test of the panels is completed. The buckling/failure loads， instability processes and failure modes of stiffened panels with different opening sizes are obtained. The results show that the buckling mode of the stiffened panel is the opposite deformation of the interbar skin and the outer skin， and the buckling mode changes several times with the increase of load. The compressive failure mode of stiffened panel is based on the buckling deformation with obvious deformation.The finite element simulation for stiffened panels with different opening sizes is carried out. The buckling and failure modes obtained are consistent with the experimental results. The error of buckling/failure load and test results is less than 4%， which verifies the validity of the finite element model. The simulation results show that with the increase of the opening size， the yield load of the stiffened panel decreases slowly at first and then increases rapidly， the failure load of the panel decreases gradually， and finally the structure loses the post-buckling bearing capacity.