Abstract: Provided are a nanotwinned silver material and a preparation method thereof. The preparation method includes: step S1, cleaning and drying a substrate; and step S2, selecting a silver target as a target, placing the substrate and the target in a magnetron sputtering equipment, vacuuming, and conducting a deposition through direct current (DC) magnetron sputtering on the substrate by applying a negative bias voltage to the substrate, where the negative bias voltage for the substrate is in a range of ?200 volts to ?50 volts, the substrate is at a temperature of 25 °C to 50 °C, a flow for argon is in a range of 30 sccm to 50 sccm, a vacuum degree of a sputtering chamber is in a range of 0.3 Pa to 1.0 Pa, and the deposition is conducted for 15 minutes to 90 minutes.