OTEC technology needs to be made more cost-effective. The Ocean Thermal Energy Conversion Association (OTECA-Japan) has been studying methods of improving OTEC plant efficiency, the optimal design of intake pipeline equipment in deep water, and multi-purpose utilization in deep water. This paper presents results from our development work on the intake pipeline system for the OTEC. A feasibility study was conducted on a large-diameter pipeline for a 1000kw OTEC plant using inexpensive high-density polyethylene with heat insulation and corrosion-proof properties. We introduced a floating pipeline system in order to avoid the need to conform to the sea floor. Our fundamental research included; 1)simulation analysis to identify static and dynamic behaviors of the pipe in tidal waves and currents, 2)experiments to identify vibrational phenomena to the pipe produced by wave-current processes and flow in the pipe, 3)experiments to measure the properties of the polyethylene. Our research indicates that this is likely suited for use in a deep water OTEC plant, although further structural study on the pipeline mooring sections and stress concentration is still needed.