This work presents a strategy for fabricating low dielectric epoxy copolymers through copolymerizing bisphenol A diglycidyl ether with N,N′-disilyl bis(secondary amine)s, a series of difunctional silylamines synthesized by silylation of bis(secondary amine)s. A study on the model reaction of monoepoxy with monofunctional silylamines identified that the reaction proceeded smoothly in tetrahydrofuran with Mg(ClO 4 ) 2 catalysis and mechanistically through sequential silylamine-induced epoxy ringopening and silylotropic N → O migration, a process with favorable Gibbs free energy changes as confirmed by density functional theory calculations. The copolymers demonstrated remarkably low dielectric constants and dielectric losses due to the formation of the low-polarizable silyloxyl instead of the hydroxyl group in polymerization and the enlarged molecular free volume. In addition, the copolymers showed desirable toughness, hydrophobicity, and thermal stability. As a tool to achieve these desirable features, the strategy developed in this work may find promising application in designing low dielectric epoxy resin materials for use in the microelectronic field.