This standard specifies the test methods for the characteristics of medium- to high-viscosity emulsions in surfactants and the evaluation of their emulsifying capacity. It is applicable to emulsion systems formed by one or more surfactants with water and water-insoluble liquids or solids. The core principle involves preparing a series of emulsions with varying concentrations through mechanical stirring, accurately distinguishing between oil-in-water or water-in-oil emulsion types using conductivity measurements, and comprehensively evaluating emulsion stability and surfactant emulsifying capacity through methods such as visual grading, storage stability observation, centrifugal separation, and microscopic particle size analysis. The key instruments used in actual testing include an electric stirrer with adjustable speed (100–500 r/min) for emulsion preparation, a conductivity meter for emulsion type determination, an optical microscope (500–1500× magnification) for observing droplet size and distribution, a centrifuge (up to 4000 r/min) for accelerated stability testing, as well as constant-temperature water baths and refrigerators for stability assessment under thermal cycling conditions.