Impact tests on CFRP laminates with three porosity levels were conducted at impact energy levels of 3,6, 9,2 and 15 J to study the influences of porosity and impact energy on the impact damage tolerance. The impact damage was evaluated by ultrasonic C-scan measurement, metallurgical microscope, thermal deply technique and visual inspections. The experimental results show that the porosity has detrimental effects on the dent depth and the damage area of composite laminates for the same impact energy. The dent depth increases rapidly with the increasing of impact energy, and a progressive increase of the impact area occurs after 9 J. The thermal deply test reveals the failure mechanism of impact damage mutation of CFRP laminates when the impact energy exceeds the threshold 9 J. The impact energy is consumed from the matrix cracks and delaminating to the fiber cracks after 9 J.