Abstract: This paper aims to develop a low passive intermodulation (PIM) absorbing box suitable for thermal vacuum environments and to verify its performance through PIM testing. An electromagnetic simulation model was established for the box and helix antennas based on the near-field absorption state inside the box. According to the dielectric constants of SiC/C foam absorbing materials at -100 ℃, room temperature, and 100 ℃, through electromagnetic simulation calculation, the design of a cone-bottom integrated high-efficiency absorbing structure on the box’s inner wall was determined. The absorbing material was shaped accordingly and assembled within a metal box. The PIM performance of the box was evaluated under thermal cycling from -90 ℃ to 100 ℃ in a vacuum. The results indicate that the PIM signal power received by the antenna remained belowx -160 dBm throughout the test, in agreement with the simulation results. This meets the low PIM performance requirement. The research provides a reference for the structural design of absorbing materials in other absorbing box types or larger PIM-absorbing boxes for satellite evaluation.