The invention relates to a nanosilver/ epoxy resin composite thermal interface material and a preparation method thereof. The nanosilver/ epoxy resin composite thermal interface material is prepared through the following method: (1) adding silver salt to a complexing agent, and performing uniform mixing so as to obtain a silver complex; and sequentially adding the silver complex, a reducing agent containing two aldehyde groups and an imidazole curing agent to epoxy resins, and performing uniform mixing so as to obtain mixed sol; and (2) pouring the mixed sol obtained in the step (1) to a mold, placing the mold in a heating box, performing heating under the constant temperature of 50-70 DEG C for 2-6h, then performing temperature rise to 90-130 DEG C, performing heating under constant temperature for 2-6h, so as to obtain the nanosilver/ epoxy resin composite thermal interface material. According to the nanosilver/ epoxy resin composite thermal interface material provided by the invention, the heat conductivity can reach 3.25W/mK, the interface heat-transfer efficiency is greatly improved, interface thermal resistance is effectively reduced, few defects exist and the properties are favorable.