A systematic theoretical investigation has been studied on Fujiwara-Moritani reaction between 3-methoxyacetanilide with n-butyl acrylate by means of density functional theory (DFT) calculations when two types of Pd(II) catalysts are employed. In [Pd(MeCN)₄](BF₄)₂ catalytic cycle, a 1,4-benzoquinone(BQ)-induced C−H activation of trans-(MeCN)₂Pd(BQ)²⁺ with 3-methoxyacetanilide occurs as the first step to give DC-4_MeCN, facilitating the insertion of n-butyl acrylate and β-hydride elimination, followed by recycling of catalyst through hydrogen abstraction of monocationic BQ fragment. In Pd(OAc)₂ catalytic cycle, it is proposed that the most favored reaction pathway should proceed in dicationic mechanism involving a BQ-assisted hydrogen transfer for C−H activation by Pd active catalyst (HOAc)₂Pd(BQ)²⁺ to generate DC-4_HOAc, promoting acrylate insertion and β-hydride elimination, followed by the regeneration of catalyst to give the final product. The calculations indicate that the rate-determining step in [Pd(MeCN)₄](BF₄)₂ catalytic system is the acrylate insertion, while it is the regeneration of catalyst in the Pd(OAc)₂ catalytic system. In particular, the roles of BQ and ligand effects have also been investigated.