Abstract: A progressive damage finite element model was established for the analysis of stiffened composite panels under transversely low velocity impact. Five typical damage modes including fiber tensile failure, matrix crushing and delamination were considered in the model. Strain-based failure criteria coupled with corresponding stiffness degradation technologies were used to predict the type and evolution of intralaminar damage modes by VUMAT user-defined subroutine. Cohesive elements were adopted in interlaminar zones and zones between stiffener and laminates to simulate the initiation and evolution of delamination through stress-based failure criteria and facture-mechanics-based failure criterion. The reasonability and effectiveness were validated by the comparison between numerical simulation results and experimental data. Finally, the influence of impact position, impact energy and initial damage (delamination) on the low-velocity impact damage of stiffened composite panels was discussed in detail.