In order to enhance the decontamination capability of nuclear facilities, a high-pressure carbon dioxide fed dry ice blasting decontamination method was proposed.Based on Fluent software,an analytical model of the flow field inside the nozzle and the decontamination chamber was established for the jet decontamination system,and the velocity distribution of dry ice particles was obtained through the flow field analysis.Using target distance,throat radius,nozzle length,dry ice particle size and pressure as key parameters and the product of impact stress of dry ice particles on the contaminated surface and distribution diameter as decontamination evaluation index,orthogonal tests for flow field analysis of 1.5 mm and 3 mm diameter nozzles were carried out respectively.By means of mean response analysis and main effect analysis,the influence law of each key parameter on the decontamination performance was grasped,and the optimal combination of parameters was obtained.The analysis results show that:after the key parameters are optimized,the decontamination performance of 1.5 mm diameter nozzle is improved by 5.64%,and the decontamination performance of 3 mm diameter nozzle is improved by 15.8%; the latter has 1.3 times more decontamination performance than the former,but the former has 3 times more CO2 utilization than the latter,providing better economy.The results of this analysis can provide support for nozzle selection and jet decontamination system parameter calculation.