Direct epoxidation of propylene (C3H6) with hydrogen (H2) and oxygen (O2) over the Au/TS-1 catalyst is known as the "Holy Grail" reaction for propylene oxide (PO) synthesis. However, Au nanoparticle loading on TS-1 was limited by traditional deposition precipitation, impregnation and could not achieve ideal catalytic results. In this report, alkaline-assisted excessive impregnation helped to remove Cl- from the Au impregnation precursor, improve the loading efficiency of Au nanoparticles and overcome the abnormal growth of nanograins. Better hydrophobicity, surface acidity and an oxygen-containing free radical environment helped Au/TS-1-AEI achieve much better C3H6 conversion (8.0%), PO selectivity (96.7%) and stability (>100 h).