Underwater blasting serves an indispensable construction technique for marine resource prospecting and ocean engineering construction. Nevertheless， the generated blast shock waves inflict varying degrees of damage on nearby reef-building corals and undermine the stability of coral reef ecosystems. Taking Cyphastrea japonica （Japanese cyphastrea） symbionts as the research object， this study reveals the physiological damage effects induced by underwater blast shock waves from three dimensions： coral host， symbiotic zooxanthellae and epibiotic microbial communities. The experimental results demonstrate that the critical shock wave resistance threshold of Cyphastrea japonica is 6.74 MPa. The total protein content of corals declines progressively with the increase of shock wave intensity， with a maximum reduction rate of 59.6%. When exposed to a blast shock wave of 11.01 MPa， the zooxanthellae density dropped by 87% and the photosynthetic capacity decreased by 49%， accompanied by obvious coral bleaching symptoms. Blast shock waves markedly suppressed the activities of superoxide dismutase （SOD） and catalase （CAT）， which meant the coral antioxidant defense system was impaired. After shock wave exposure， the epibiotic microbial communities presented significantly elevated diversity at the phylum taxonomic level and more complex community composition at the genus level. This work elucidates the stepwise damage evolution pathway of coral host–zooxanthellae photosynthetic system–microbial communities caused by underwater blast shock waves， and provides a scientific theoretical basis for coral reef ecological protection during ocean blasting engineering.