The invention discloses a vacuum lock system for transmitting substrates. The vacuum lock system comprises a cavity body, a substrate support assembly and an elevating mechanism; the cavity body comprises a first cavity and a second cavity, two openings which can be connected to the atmosphere environment or the vacuum processing environment are formed in the sidewall of the second cavity, and the first cavity carries out plasma processing on the substrate therein; the substrate support assembly is arranged in the cavity body in a liftable manner, and comprises a partition plate, a first support member and a second support member, the partition plate, the first support member and the second support member are stacked vertically, and the first and second support members bear the substrate; the elevating mechanism drives the substrate support assembly to move between a first position and a second position. In the first position, the partition plate seals up a bottom opening of the first cavity, the first support member is arranged in the first cavity, and the second support member corresponds to the two openings in the sidewall of the second cavity. In the second position, the first support member corresponds to the two openings. According to the invention, the substrate processing efficiency can be improved, and the movement load of a transmission robot is alleviated.