Hazard and operability (HAZOP) analysis, layer of protection analysis (LOPA) and the safety integrity level (SIL) risk reduction value methodology are employed to assess the safety of an ammonia/carbon dioxide cascade refrigeration system. By analyzing the potential risks, hazards and possible deviations during operation are identified, the effectiveness of existing safety control measures is assessed, and the risk reduction achieved is quantified. The HAZOP method effectively identifies potential hazards in the system; the LOPA method helps quantify risks and reduce the frequency of risks associated with independent protection layers; the SIL risk reduction value methodology provides a quantitative basis for evaluating the effectiveness of risk mitigation. The analysis results indicate that the risk reduction target for the evaporator side (ammonia refrigeration side) is 71, with a safety integrity risk reduction value of -0.14, necessitating the addition of safety equipment with a safety integrity level (SIL) of 1 to ensure system safety. It is also recommended that the safety evaluation and analysis of this refrigeration system be emphasized during the development of industry standards.