A last-stage LP turbine is a potential way to increase the efficiency of a steam turbine. The primary objective of this study is to investigate the characteristics of the performance parameters in the last stage of the LP steam turbine, which explores the single-phase flow in steady-state three-dimensional Computational Fluid Dynamics (3D CFD) for the stator-rotor interaction by comparing two models for the rotor blade that rotates with and without lacing wire due to variation three time of target mass flow rate with pressure inlet. ANSYS-Fluent is the best software used for computation using the steady-state flow model. The performance of the steam turbine derives from CFD results in the static pressure, the torque on the rotor blade, and the flow structure around the lacing wire. And the FEA releases the result of equivalent stress, strain, and total deformation of the rotor blade. Comparing the internal flow features of the final stage blade in the two models with and without lacing wire, it is clear that the model with lacing wire suffers from an energy loss larger and that the flow is not very smooth where the lacing wire locate. Finally, the high torque is for the model without a lacing wire, while the model with a lacing wire has a lower torque than the model without a lacing wire. The maximum stress is in the elastic zone and at the leading rotor blade for the model without lacing and at the interaction of the lacing wire with the rotor blade. The maximum strain is consistent with maximum stress. The maximum deformation, both models appear at the tip for all variations.