Abstract: It has been confirmed by testing that the oil backstreamingcontamination of the oil diffusion pump system formed very harmful ef- fects on tested satellite.The technological transforming,replacing the 4oil diffusion pump by 3 ZDB-1300 helium refrigerator cryopumps will beintroduced in this paper.The performance comparison of the new systemwith old system will be given.The successful using of new system in thethermal balance test for returnable satellite will be presented also.