In the discharge pumping process of xenon lamp, there is a significant pyrolysis process of the materials in the cavity of the slab amplifier under the irradiation of high intensity xenon light, which produces a large number of micron sized suspended particles. For the online cleanliness control of the amplifier, a series of effective measures were taken, including the selection of materials conducive to the cleanliness control, elimination of blind holes and welds, deep pickling and etching, high-pressure spray cleaning and final light cleaning. The experimental results show that after 100 times of light cleaning, the aerosol particles in the chamber are between 300 and 1000, which is close to the cleanliness level of the American National Ignition Facility (NIF) Project; After the operation of the generator is completed, the amplifier chamber is purged with a mixture of nitrogen and oxygen of about 0.4 m/s, and the aerosol particles can recover to zero within 2 minutes.