Combined theoretical and experimental studies have explained the mechanism of Pd-catalyzed δ-C(sp3)?H arylation of primary amines. Instead of the monomeric Pd mechanism, our research unveils that all steps including C-H activation, oxidative addition, and reductive elimination take place via the heterodimeric Pd-Ag intermediates and transition states. Experimentally, the active heterodimeric Pd-Ag species were detected by mass spectrometry, which further confirms the proposed heterodimeric mecha-nism. Insight gained through this study reveals the synergistic manner of palladium catalysis and silver(Ⅰ) additives in native NH2-directed C-H activation and C-C coupling reactions.