The invention discloses a vacuum incinerator. The vacuum incinerator is a JZK-C well type vacuum incinerator and comprises a vacuum hearth, an incinerator cover opening and closing device, electric heating pipes, a waste collecting system, a vacuum pipeline anti-blocking device, a water spraying device, a water ring vacuum pump, a water backflow preventing device, a gas-water separator, a control system, a water circuit, an air circuit and the like, wherein the vacuum hearth is horizontally placed with an incinerator opening facing upwards and composed of an incinerator cover and a work room used for storing cleaned parts. The waste collecting system mainly comprises a waste collecting tank which is installed on the lower portion of the hearth. A hopper-shaped tray is arranged at the bottom of an inner cavity of the vacuum hearth. A discharging port of the tray is located over the waste collecting tank. Compared with the prior art, the vacuum incinerator is compact in structure, good in sealing performance and large in work space; the incinerator cover is opened and closed through two oil cylinders, the cover opening angle is larger than 90 degrees, and the opening and closing stability of the incinerator cover is guaranteed; waste can be collected conveniently, incineration and cleaning are conducted efficiently, and the situation of water backflow can be effectively prevented; and the automation level is high, temperature control is accurate, the working efficiency is improved, and the labor intensity is relieved.