<p>The introduction of a second metal into Au/TS-1 can increase the number of active sites and control the size of metal particles to enhance catalytic activity. In this study Au-Fe bimetallic catalyst Au-Fe/TS-1 was prepared by the deposition-precipitation (DP) method, the structure and morphology of the catalyst were characterized by XRD, BET, and HRTEM. The effects of Fe source (such as Fe(NO₃)₃, Fe₂(SO₄)₃, NaFeEDTA) and Fe/Au ratio on propylene epoxidation performance were systematically investigated. The facile hydrolysis of Fe³⁺ and the absence of ligand coordination resulted in substantial coating of the TS-1 surface with Fe(OH)₃ which severely impaired propylene oxide (PO) selectivity and promoted the peroxidation reaction. However, using NaFeEDTA as Fe source can significantly inhibit excessive Fe deposition and the Au nanoparticles of Au-Fe/TS-1 is around 2&#xa0;nm (smaller than the 3&#xa0;nm in Au/TS-1). The synergistic effect of Au-Fe enhances the epoxidation activity of the catalyst, thereby increasing the rate of PO formation. Specifically, the optimal catalyst, Au-Fe_0.2(E)/TS-1(using NaFeEDTA as Fe source), achieved a maximum PO formation rate of 146 g_PO·h⁻¹·kg_Cat⁻¹ at 200&#xa0;°C (significantly higher than 96 g_PO·h⁻¹·kg_Cat⁻¹ of Au/TS-1), with PO selectivity exceeding 90%. These findings provide valuable insights for the rational design and development of more efficient Au-M bimetallic catalysts.</p> Graphical Abstract <p></p>