The invention discloses a vacuum arc-extinguishing-chamber burn-in device of a direct-current superposed high voltage pulse and a method thereof. The device comprises a direct current power supply, a pulse power supply, a vacuum arc-extinguishing chamber, a blocking coupling capacitor and an isolation inductor. One end of the direct current power supply and one end of the pulse power supply are connected to one end of a vacuum arc-extinguishing chamber contact. The other end of the direct current power supply is connected to one end of the isolation inductor. The other end of the pulse power supply is connected to one end of the blocking coupling capacitor. The other end of the blocking coupling capacitor and the other end of the isolation inductor are connected to the other end of the vacuum arc-extinguishing chamber contact. By using the device and the method, technology difficulty is small, cost is low, and simultaneously single burn-in energy can realize accurate adjusting.