Model tests have been conducted on flexible submarine pipelines over flat beds subjected to steady flow in the wave-current flume with 55m in length, 4m in width and 2.5m in depth. The pipelines are made by flexible pipe with 60mm in diameter and placed at various distances from a flat bed. Gap to diameter ratio varied from 0.4 to 1.2 when the pipelines are not sagging. The flow velocity in the model tests ranged from 0.35 m/s to 0.6 m/s and water depth is 0.4m. The Reynolds numbers ranged from 2.1 x104 to 3.6x104 within the subcritical Reynolds numbers range. Bending strain was measured by strain gauges bonded on the inner surface of the pipeline. The feature of dynamic response is analyzed and discussed in time domain and frequency domain against various gaps between the pipeline and the flat bed.