For the risk of damage to built submarine pipelines caused by underwater blasting construction in marine engineering, taking the reef blasting in harbor dredging engineering adjacent to submarine pipelines as an example, this paper systematically describes and analyzes key thinking and technical applications of underwater blasting construction, and it mainly focus on the protection of the submarine pipelines during construction.The conclusion indicates that compared with underwater exposed blasting methods, underwater drilling blasting is a better method in blasting efficiency, consumables, and protection of surrounding structures.In blasting construction, the explosive quantity is the core of controlling the vibration speed of pipelines.It is necessary to calculate the relationship between explosive quantity and safety distance based on the allowable vibration speed of pipeline before construction, and design a safe detonation network for different blasting distances combined with equipment and materials.By setting weakened vibration holes and groove, the vibration transmission caused by underwater blasting can be further reduced, and the risk of vibration damage to pipelines can be lowered.Vibration monitoring can timely observe and collect the vibration status of pipelines during underwater blasting, providing a reference for adjusting construction methods or analyzing pipelines safety, and the pipeline integrity testing after construction is an important method to ensure the safety use of pipelines in production.