Abstract: The highly radioactive hot cell is used as an auxiliary facility for the irradiation inspection of reactor materials, and the hot cells are with high radiation level, complicated structure and great difficulty in decontamination. In view of the particularity and complexity of the decontamination of the decommissioned stainless steel shell in the strong heat release chamber, this paper is carrying out three single-item decontamination tests and decontamination process test studies on the high-pressure water jet decontamination, the strippable film decontamination and the mechanical polishing decontamination. On the basis of this, an innovative composite decontamination process for stainless steel shells in a strong heat release chamber was innovatively proposed. The engineering decontamination practice verified that, the average level of contamination on the surface of the stainless steel cladding after the decontamination is below 40 Bq/cm². The factor is as high as 110 or more, reaching the domestic advanced level. The research and development of the high-efficiency compound decontamination technology in the hot cell solves the technical problem of the decontamination of the stainless steel shell surface in the highly radioactive hot cell, reduces the exposure dose of workers in the decommissioning stage, protects the safety of workers and the environment, and has significant economic and social benefit.