Objective To summarize and improve the related technical issues by analyzing the nationwide interlaboratory comparison of gross α and gross β radioactivity measurement over the years. Methods According to the requirements of interlaboratory comparison and the national standards, the gross α and gross β radioactivity in water were measured, and the results were analyzed to identify the influencing factors. Results From 2018 to 2022, our laboratory participated in five nationwide interlaboratory comparisons of gross α and gross β radioactivity measurement. The Z-test values for gross α and gross β measurement ranged from −0.24 to 1.8 and −1.4 to 0.35, respectively. The relative deviations ranged from −4% to 32% and −18% to 6%, respectively. All comparisons were within the acceptable ranges. Conclusion The analysis of comparisons showed that the results were within the acceptable ranges. The relative deviations between the measurement and the reference values have decreased over the years. The summary and improvement of related technologies have improved the measurement accuracy.