In order to figure out the dynamic characteristics of the pipeline and cable during pipeline end termination (PLET) installation based on S-laying, numerical simulation is carried out based on a practical operation project performed at Liwan oil and gas fields in the South China Sea. Four scenarios are selected from the PLET installation process in sequence for simulation. Critical responses of the pipeline and the cable in different scenarios of the operation are analyzed in this paper with a coupled model using RIFLEX module of SIMA software. Both the pipeline and the cable are modeled by the finite element method, and the pipelaying vessel is controlled by a dynamic positioning system. The simulation results are validated by the commonly used OrcaFlex software. The critical responses analyzed include static configuration, time-domain variation of axial tension at the top of the cable and bending moment variation near the touchdown point (TDP) of the pipeline. Furthermore, the time-domain variation of the tension at the top of the cable under different wave and current directions are also compared and analyzed, in order to study the effect of sea environment on the pipeline and cable during PLET installation operation. The results show that the responses of pipeline and cable vary in different operation scenarios, and the sea environment has remarkable effect on the pipeline and cable. The study in this paper is of value to the design of PLET installation based on pipelaying and can help predict the response of pipeline and cable during the operation.