GB/T 29024.2-2025 "Particle size analysis - Single particle optical sensing methods - Part 2: Light scattering liquid-borne particle counter" is applicable to measuring the size and number concentration of particles ranging from 0.1 μm to 10 μm suspended in liquids. It replaces the previous version of the standard and optimizes technical requirements. The standard specifies the light scattering method based on single-particle scattering measurement, defines core performance indicators such as particle size setting error, counting efficiency, and resolution, and includes requirements for controlling sampling flow rate, time, and volume errors. New sections on principles and basic configurations have been added, and the definitions of calibration particle terms and calibration procedures have been revised. It is applicable to the evaluation of pure water and chemical reagent cleanliness, as well as the detection of particle characteristics in various liquids. The standard provides unified criteria for instrument measurement, calibration, and verification, ensuring the accuracy and consistency of test results.