This article focused on a retired Co irradiation facility site in Jiangsu Province. A new high-recovery-rate soil sampling device was used to collect soil and groundwater samples for laboratory analysis. Concurrently， Surface Contamination Measuring Instruments and Portable X-ray Radiation Dose Rate Meters were utilized to monitor beta surface contamination and the gamma radiation airabsorbed dose rate. The results of the monitoring analysis showed that ⁶⁰Co was not detected in the soil and groundwater samples， and the detected concentration of ¹³⁷Cs in the soil samples all reached the clean release levels specified by the national standard， while the surface contamination of beta was lower than the standard release level. The air-absorbed dose rate of gamma radiation was within the normal fluctuation range of environmental radioactivity levels in Jiangsu Province. This indicated that the entire irradiation room area of the irradiation decommissioning site did not cause environmental pollution during operation and on-site decommissioning and could reach the level of unrestricted openness. Simultaneously， the application of new high-recovery-rate soil sampling devices has significantly improved sampling efficiency and accuracy， providing robust support for soil and groundwater environmental investigations.