The utility model discloses a high vacuum system. The high vacuum system comprises a plurality of roots vacuum pumps, a plurality of rotary vane pumps and a slide valve pump; the plurality of rotary vane pumps are connected with the sliding valve pump in parallel, and then are connected with the plurality of roots vacuum pumps in series; one ends of the roots vacuum pumps are connected with a reactor in a sealing mode. The high vacuum system comprises the plurality of roots vacuum pumps in serial connection, is high in vacuum degree and low in noise, the energy consumption and maintenance costs are low, and the vacuum degree can reach 0.1pa minimally.