The utilization of π-type composite stiffened panels plays a pivotal role in effectively distributing intricate loads, finding widespread application in both primary and secondary load-bearing structures of aircraft. Despite its significance, the composite material is susceptible to impact from foreign objects during routine use, making it crucial to understand its impact response characteristics and residual strength for ensuring the safe operation of aircraft. This study focuses on subjecting the center of a π-type stiffened panel to impact, followed by conducting a residual strength test on the specimen post-impact. Employing continuum damage mechanics, three-dimensional numerical simulations were conducted to analyze the impact and residual strength. The Hashin-criterion of three-dimensional strain was modified using the damage failure criterion of monolayers, and stiffness degradation principles based on fracture toughness were applied to model material stiffness reduction. Cohesive elements were utilized to predict layered damage evolution. Both numerical analysis and experimental investigations were employed to analyze the impact damage and residual strength of the π-type composite stiffened panels at low velocity impact. The congruence between the numerical calculations and experimental measurements suggests that the model accurately predicts impact damage and residual strength for reinforced composites at low velocity impact.