The invention discloses a vacuum impregnation method, and belongs to the technical field of vacuum impregnation. The vacuum impregnation method comprises the following steps of: 1, preheating, namelyheating a
capacitor; 2, canning, namely putting the heated
capacitor into a dipping tank in a tank body; 3, vacuumizing, , namely starting a vacuum unit to keep a negative pressure state in the tank body; 4, gas charging, namely charging
argon into the tank body; 5, heating, namely heating the interior of the tank body; 6, secondary vacuumizing, namely starting a vacuum unit, and controlling the vacuum degree in the tank body to be below 8Pa; 7,
liquid injection and impregnation, which is implemented by injecting an
electrolyte into the
capacitor to impregnate the capacitor for 1013 hours, andkeeping
constant pressure and constant temperature during impregnation; and 8, taking out, namely stopping heating the tank body, and taking out the capacitor after the tank body returns to a normal-temperature and normal-pressure state. The vacuum impregnation method is simple in process, good in impregnation effect and high in impregnation efficiency, and the product performance is improved.