Abstract: 【Objective】 To evaluate the capability of laboratories of radiological health technical service institutions in Shanghai to measure gross alpha and gross beta radioactivity in water.【Methods】 All local laboratories with operational scope covering gross alpha and gross beta radioactivity measurement (hereinafter referred to as "participating laboratories") were organized to undertake a proficiency test. According to GB/T 5750.13-2023 Standard Examination Methods for Drinking Water-Part 13: Radioactive Indicators and GB/T 28043-2019 Statistical Methods for Proficiency Testing Using Interlaboratory Comparisons, the comparison results were uniformly assessed using z-scores.【Results】 In all years, every participating laboratory adopted the evaporation concentration-α/β counting method. In the 2023 provincial-level comparison, 15 laboratories participated, with a pass rate of 86.67% (i.e., both gross alpha and gross beta results ≤ 2.00) and no laboratory achieved "excellent" (i.e., both gross alpha and gross beta results ≤ 0.50). In 2024, 19 laboratories participated, achieving a pass rate of 100% and an excellence rate of 21.05%.【Conclusion】 Compared with 2023, both the pass rate and the excellence rate in 2024 improved significantly, indicating that the capability of the participating laboratories to measure gross alpha and gross beta radioactivity in water has been effectively enhanced. By improving the testing capability of technical service institutions, this proficiency testing program helps prepare for potential future public health emergencies.