Multistage vacuum pumping device and method of ozone low-temperature sterilization device

The invention provides a multistage vacuum pumping device and a multistage vacuum pumping method of an ozone low-temperature sterilization device, and belongs to the technical field of sterilization equipment. The multistage vacuum pumping device comprises a first-stage oil-free vacuum pumping device and a second-stage oil-containing vacuum pumping device which are connected in parallel through a pipeline, wherein after the two stages of vacuum pumping devices are connected in parallel, one ends of the vacuum pumping devices are connected to a sterilization cabin, the other ends of the vacuum pumping devices are connected to an ozone decomposing device, and a drying device is connected to the sterilization cabin through a pipeline. The multistage vacuum pumping method comprises the following steps: firstly pumping out most of ozone in the sterilization cabin by using the oil-free vacuum pumps, then injecting dry sterile air, and repeating the steps several times. The multistage vacuum pumping method can be used for pumping out most of the ozone in the sterilization cabin, and then the vacuum degree in the sterilization cabin is reduced to below 100Pa by using the oil-free vacuum pumps. Two vacuum pumping manners are in cascade connection so as to ensure that the vacuum degree in the sterilization cabin is lower than 100Pa, and avoid the reduction of the vacuum pumping capacity due to the oxidization of sealing oil which is caused by using an oil-containing vacuum pump for pumping the ozone.