In order to study the dynamic response of undersea tunnels in the case of explosions, explicit dynamic analysis software LS-DYNA is used to establish a finite element model, and through the test data and the U.S. Explosive Manual TM5-855-1 empirical formulas to validate the reliability of the model, and the underwater explosion under the propagation of blast waves action is studied, the process is from the water-soil interface to soil and then the structure. The tunnel structure response dynamic analysis is discussed, at the same time the charge equivalent and cover depth on the structural response of the tunnel. Results show that an increase in the charge equivalent and reduce the depth of cover will cause an increase in the structural pressure, velocity and displacement, impact on the structure from top to bottom of the tunnel gradually weakened, and with the increase in the depth of soil cover, impact on tunnel structure is gradually reduced.