Abstract: This study investigates a 750 kV substation project， focusing on the mechanical behavior of expanded aluminum stranded conductors （JLHN58K-1600）. The flexural rigidity of the conductors was obtained through three-point bending tests. A finite element model of the substation’s overhead-downlead conductor system was established to analyze the mechanical responses of conductor stiffness models considering flexural rigidity under multiple working conditions and parametric variations. The analysis results indicate that the mechanical performance of the conductors is highly sensitive to structural span and layout configuration. As the span and the height difference between the two ends increase， conductor tension increases significantly. Notably， for overhead conductors， a span of 30 meters conductors serves as a critical threshold， beyond which the increase in horizontal tension becomes more pronounced. The layout of downlead conductors also influences the load-bearing behavior of the structure. Compared with single-vertical （straight-line） configurations， V-shaped （inverted-V） downleads provide additional horizontal constraints， effectively reducing lateral displacement and vibration， and consequently decreasing conductor tension. A combined use of straight-line and V-shaped downleads further distributes the load， minimizing overall conductor tension.