Abstract: The pipeline has become an important way for the transmission of oil, gas and other fluid in China. However, floating accidents of shallow pipelines often occur in coastal soft clay areas, which seriously threaten the security of energy lifeline engineering. A set of test devices and methods for buoyancy of pipeline are proposed. Full scale model tests on commonly-used gas pipeline are carried out to get pipe-soil interaction and pipeline buoyancy in soft clay with different disturbance degrees, and then the mechanism of pipeline floating is revealed. Furthermore, a calculation method for prediction of buoyancy of pipelines, which is related to the undrained shear strength of backfill soft clay, is proposed based on the test results of buoyancy of pipelines in several batches of backfill soft clay with different disturbance degrees.