This paper will use the dynamic analysis program ANSYS/LS-DYNA to establish a numerical model of underwater drilling and blasting. Considering the effect of water weight, the effects of underwater rock drilling and blasting under different initiation methods and different blocking materials are analyzed, and the results are obtained respectively Pressure time history graph, velocity time history graph and vertical stress time history graph. The results show that the blasting effect of rock under different initiation methods and different blocking materials is different, and the blasting effect in different parts is also affected by the initiation method and the blocking material, however, the effect of a single plugging material on the rock breaking effect is not great, especially at the position of the rock-water contact surface, under the effects of water material blockage and gun mud material blockage, the blasting at both ends makes the stress disturbance generated by rock blasting more uniform, and the overall blasting effect is good. Therefore, in actual engineering, different initiation methods and blocking materials should be selected according to the blasting focus to better achieve the expected blasting effect.