This study focuses on a new technology of Subsurface Tension Leg Platform(STLP),which utilizes the shallowwater rated well completion equipment and technology for the development of large oil and gas fields in ultra-deep water(UDW).Thus,the STLP concept offers attractive advantages over conventional field development concepts.STLP is basically a pre-installed Subsurface Sea-star Platform(SSP),which supports rigid risers and shallow-water rated well completion equipment.The paper details the results of the parametric study on the behavior of STLP at a water depth of 3000 m.At first,a general description of the STLP configuration and working principle is introduced.Then,the numerical models for the global analysis of the STLP in waves and current are presented.After that,extensive parametric studies are carried out with regarding to SSP/tethers system analysis,global dynamic analysis and riser interference analysis.Critical points are addressed on the mooring pattern and riser arrangement under the influence of ocean current,to ensure that the requirements on SSP stability and riser interference are well satisfied.Finally,conclusions and discussions are made.The results indicate that STLP is a competitive well and riser solution in up to 3000 m water depth for offshore petroleum production. This study focuses on a new technology of Subsurface Tension Leg Platform (STLP), which utilizes the shallow water rated well completion equipment and technology for the development of large oil and gas fields in ultra-deep water (UDW) .Thus, the STLP concept offers attractive advantages over conventional field development concepts. STLP is basically a pre-installed Subsurface Sea-star Platform (SSP), which supports rigid risers and shallow-water rated well completion equipment.The paper details the results of the parametric study on the behavior of STLP at a water depth of 3000 m. At first, a general description of the STLP configuration and working principle is introduced. Chen, the numerical models for the global analysis of the STLP in waves and current are presented. After that, extensive parametric studies are carried out with regarding to SSP / tethers system analysis, global dynamic analysis and riser interference analysis. Critical points are addressed on the mooring pattern and riser arrangemen t under the influence of ocean current, to ensure that the requirements on SSP stability and riser interference are well satisfied. Finally, conclusions and discussions are made. The results indicate that that STLP is a competitive well and riser solution in up to 3000 m water depth for offshore petroleum production.