A plastic forming and gradient toughening method based on ultrasonic vibration, characterized in that the toughening method comprising: (a) according to actual use requirements of an amorphous alloy part to be formed, dividing one or more portions to be toughened on the amorphous alloy part to be formed, the portion being used for generating a nanocrystalline toughening phase and an amorphous state of other portions being retained; (b) designing a toughening device for forming the amorphous alloy part to be formed, wherein the toughening device is connected to an external drive mechanism and comprises one or more inserts connected to an ultrasonic vibration amplitude transformer and one or more resistance heating rods, the insert is disposed corresponding to the portion to be toughened and used for applying ultrasonic vibration to the portion to be toughened, the one or more resistance heating rods are used for heating raw material blank to be processed to a forming temperature, and parameters of the ultrasonic vibration generated by the ultrasonic vibration amplitude transformer are obtained by analyzing an energy propagation process of the ultrasonic vibration by finite element numerical simulation, in which energy of the ultrasonic vibration is adjusted by adjusting an amplitude, a frequency and a power of the ultrasonic vibration, and when the energy of the ultrasonic vibration exceeds an energy threshold value required for nanocrystallization, the corresponding amplitude, frequency and power of the ultrasonic vibration are required parameters of the ultrasonic vibration; and (c) placing raw material blank in the toughening device, heating the raw material blank by the one or more resistance heating rods to a forming temperature, and performing mold closing of the toughening device to form a required amorphous alloy part, ultrasonic vibration being started in the mold closing process and stopped when mold opening is performed. (a) according to actual use requirements of an amorphous alloy part to be formed, dividing one or more portions to be toughened on the amorphous alloy part to be formed, the portion being used for generating a nanocrystalline toughening phase and an amorphous state of other portions being retained; (b) designing a toughening device for forming the amorphous alloy part to be formed, wherein the toughening device is connected to an external drive mechanism and comprises one or more inserts connected to an ultrasonic vibration amplitude transformer and one or more resistance heating rods, the insert is disposed corresponding to the portion to be toughened and used for applying ultrasonic vibration to the portion to be toughened, the one or more resistance heating rods are used for heating raw material blank to be processed to a forming temperature, and parameters of the ultrasonic vibration generated by the ultrasonic vibration amplitude transformer are obtained by analyzing an energy propagation process of the ultrasonic vibration by finite element numerical simulation, in which energy of the ultrasonic vibration is adjusted by adjusting an amplitude, a frequency and a power of the ultrasonic vibration, and when the energy of the ultrasonic vibration exceeds an energy threshold value required for nanocrystallization, the corresponding amplitude, frequency and power of the ultrasonic vibration are required parameters of the ultrasonic vibration; and (c) placing raw material blank in the toughening device, heating the raw material blank by the one or more resistance heating rods to a forming temperature, and performing mold closing of the toughening device to form a required amorphous alloy part, ultrasonic vibration being started in the mold closing process and stopped when mold opening is performed.