In the process of ocean development, blasting excavation of underwater coral reef limestone is often involved.In order to study the fracture characteristics of coral reef limestone after underwater drilling and blasting, four types of coral reef limestone were used to simulate single hole blasting tests under three water depth conditions.The failure zone around the hole, radial crack and fragmentation distribution of reef limestone specimens under different water depth were analyzed.The results show that no obvious failure zone around the hole is observed in coral limestone and coral gravel limestone specimens.For the biological gravel limestone, obvious cavity can be observed on the surface around the blast hole.The number and width of apparent cracks of the specimen after blasting decreases with the increase of the water pressure.The boulder yield increases with the increase of water depth, and the block size distribution of underwater drilling and blasting of coral reef limestone conforms to the swebrec distribution.