Underwater explosives that left in ports and harbors during World War II, which may not be inspected in reconnaissance surveys could threat submerged pipelines seriously. This paper developed a three-dimensional numerical model for dynamic response of pipelines induced by underwater explosion. Both FSI (Fluid-Structure interaction) and PSI (Pipeline-Seabed interaction) are taken into consideration simultaneously in current research. The proposed integrated model has been validated against experiment data available in previous literature. It has been found that the pipeline laid on the seabed tends to roll away from detonation rather than to deform in the pipeline section. The semi-buried pipeline is the most vulnerable due to combined action of reloading effect and trench constraint. Based on the numerical results, shallow buried installation is an effective method to enhance the anti-blast ability of submerged pipelines. The stress level of the pipeline increases slightly due to enhancement of the surrounding soil for shallow buried pipelines, while the integral lateral displacement and element pressure decrease with increase of burial depth.