A method and device for controlling viscosity of asphalt rubber based on a current variation are provided. The method includes processing asphalt rubber raw materials with a first preset proportion, and shearing the processed asphalt rubber; obtaining a shearing current, pumping and discharging the sheared asphalt rubber; obtaining a discharging current, and obtaining the viscosity of the pumped asphalt rubber according to the discharging current and the viscosity-discharging current correlation relationship. The method includes comparing the viscosity with a preset viscosity; outputting the pumped asphalt rubber as finished asphalt rubber when the viscosity is equal to the preset viscosity. The method includes adjusting the viscosity according to the discharging current. Double-current control is adopted, so that the whole-process control of the processing viscosity of the asphalt rubber is realized, and the control accuracy of the viscosity is improved.