Abstract: The dynamic characteristics of underwater explosion bubbles near free surface are very complicated, which is of great significance to studying the mechanism of damaged structure subjected to a second attack by weapon. Based on the coupling Euler-Lagrange (CEL) method, a numerical model of near-free surface underwater explosion was established. The dynamic characteristics of the bubbles in the underwater explosion process of the near-free surface of the (intact) right-angle structure were discussed. The coupling mechanism between the near-free surface underwater explosion bubbles and the damaged structure were revealed. Firstly, the underwater explosion model of near-free surface was established. In order to verify the effectiveness of numerical method, the obtained numerical results such as bubble morphology, maximum radius and period were compared with experimental data. The dynamic characteristics of underwater explosion bubbles near complete and damaged structures were compared. It is found that the joint action of structure and free surfaces causes the bubbles to experience jet deflection, depression on the side of the water mound and bubble fragmentation. The results also show that when the hole size of the damaged structure ranges from 0.070 to 0.085 times of bubble radius, a tilting jet is formed on the side of the structure. The increase of the hole size has a significant positive effect on the head width, head speed and tilt angle of the jet.