This standard establishes a standardized procedure for determining the water content in natural gas using the oscillating frequency difference method, providing critical technical support for quality monitoring, trade transfer, and safe transportation of pipeline natural gas. Its core principle is based on the change in the natural frequency of an oscillator coated with a sensitive hygroscopic material upon adsorbing moisture. By precisely measuring the frequency difference, trace amounts of moisture in the gas can be quantitatively analyzed, with a detection range covering a broad interval from 5 parts per million to 2,000 parts per million. In practical testing, continuous measurements are primarily conducted using online moisture analyzers based on the oscillating frequency difference method. These instruments are typically equipped with a measurement cell and a sealed reference cell. Through built-in detection elements, they sense frequency changes in real time and incorporate precise mass sensitivity coefficients for calibration and conversion, thereby ensuring high precision and stability of test data in high-pressure pipeline transmission environments.