The dynamic unbonded flexible riser which is the key equipment in the offshore petroleum industry owns some advantages such as easy installation, high reliability and high anti-fatigue property. The dynamic unbonded flexible riser is manufactured by twining with polymer layers and steel tape layers. The section stiffness of flexible riser is in the relative low level compared with soild steel pipe, and it is easy to move when facing to the current, so the flexible riser configuration must be specially designed to avoid the interaction between the risers and mooring lines. We use the Huse wake model and finite element method (FEM) to analyze the flexible riser and mooring line in the South China Sea environment, meanwhile perform the sensitivity analyses of riser section stiffness, pipe flow density and drag coefficient. Finally, some engneering meaningful conclusions are given.