This study optimizes accelerometer placement for vibration signal acquisition in Electro Transmission (ET) units to support Prognostics and Health Management (PHM) dataset construction. HyperMesh finite element models of ET housing sub-components are developed and validated through impact hammer modal testing, correcting material properties and boundary conditions. These validated sub-models are assembled into an integrated ET model. Romax multi-body dynamics simulations provide bearing support reaction forces from the internal planetary gear system; these forces are converted into the frequency domain and applied as excitation inputs. Vibration response under typical operating conditions is analyzed using the modal superposition method. The Modal Assurance Criterion (MAC) calculates characteristic vibration modes, forming an objective function for Particle Swarm Optimization (PSO) to determine optimal accelerometer locations. Hardware-in-the-loop (HIL) testing validates the optimized layout, with acquired signals demonstrating strong auto-correlation and cross-correlation, confirming the method's effectiveness. This work provides a theoretical basis for ET vibration monitoring and PHM dataset development.