Abstract: A two-dimensional radiation diffusion hydrodynamic code LARED-S is used to investigate evolution behavior of a penetrating defect and its influences on square-pulsed DD cryogenic capsule implosion performance. It shows that a penetrating defect on DD ice layer reduces significantly the neutron yield with a YOC of 23.8%. The defect makes the Si-doped CH ablator layer produce a high-amplitude inward-facing spike, penetrating into the central DD gas. A large amount of ablation material is mixed into the hot spot with a mixing mass of 487 ng, leading to a significant increase in the bremsstrahlung radiation loss power from the hot spot compared to the 1D ideal implosion result. It results in a large reduction in the hot-spot temperature and the final DD reaction rate. Meanwhile, the high-density shell spike pushes the hot spot away from the capsule center, exhibiting a great P1 asymmetry. The P1-asymmetric hot spot has an obvious bulk flow velocity, which reduces the conversion efficiency of implosion kinetic energy into the internal energy of the hot spot.