A Tender Assisted Drilling (TAD) is typically a support vessel that serves support of a drilling rig, by offering comfortable accommodation for crew and providing additional space where the Drilling Equipment Set is stored and transported. The operation with TAD provides an economical and flexible way for offshore drilling, especially with TLP. Dynamic response of tender-assisted drilling system is crucial due to the safety concern. However, some urgent issue has not been thoroughly studied in tender assisted drilling operation like the hydrodynamic interaction and the impact of nonlinearity cable used. In this paper, a tender assisted drilling system which was taken as the research object was investigated under the metocean conditions of West Africa. The numerical model was established in frequency domain using 3D multi-body diffraction/radiation wave theory and the hydrodynamic interaction is studied in this part. Then two kinds mull-body system with different hawsers arrangements are analyzed by the time domain simulation was performed considering hydrodynamic interaction and the impact of nonlinearity of mooring lines and hawsers. The Time history results of floating body motion and the force on mooring line is compared between two schemes. The results obtained is also investigated by spectral analysis to clearly understand the coupled behavior of such system under these two arrangement.