When drilling blasting under deep water,a reasonable plugging length cannot only improve the blasting effect but also save construction cost.In order to study the reasonable value of plugging length for deep water drilling blasting under deep water conditions,we use a single variable method to only change the plugging length,and apply ANSYS/LS-DYN software to conduct numerical simulation research on underwater drilling blasting combining with waterway regulation project of Liantuo River between the Three Gorges Dam and Gezhouba Dam.The results show that as the water depth increases,the water pressure on the rock mass also increases accordingly.The water pressure can replace part of the blockage.As a result,the reasonable plugging length should decrease with the increase of the water depth.Under the four typical deep water conditions of 20 m,25 m,30 m,and 35 m,the corresponding reasonable plugging lengths are 140 cm,120 cm,100 cm and 80 cm.When the same charge structure of the explosive drilling blasts at different water depths,the reasonable plugging length and water depth are approximately linearly related.