Deepwater pipelay has in a few years time become safe and economical. Although the various installation methods have proven their suitability and each have their specific advantages, selection of pipelay method is dependent on key parameters like pipe type, size and material, barge category, installation equipment water depth and wave & current loading conditions. Between S-Lay and J-Lay, there are significant differences mainly in the system to control the horizontal tension to limit sagbend and overbend stresses, the ability and limitation for applying axial tension at the surface and ability to accommodate pipe departure angle. Due to the numerous parameter to be considered when selecting the appropriate method, this research thesis provides a comparative study of the key parameters which effects the stresses induced during installation process for both S-Lay and J-Lay methods. In this research work,　　 different case studies with variation in pipe size, water depth, wave & current direction and departure angle for S-Lay and J-Lay methods have been done through FEA software Orcaflex, and structural response and stresses generated have been discussed in accordance with analysis results acquired. This research study may provide guidelines for the preliminary pipeline installation design.