GB/T 2539-2008 stipulates that the melting point of petroleum wax should be determined by the chill down Linear dispersion method. It is suitable for all kinds of petroleum wax products. When measuring, the petroleum wax is heated to complete melting, and then chilled down in a specific environment. The temperature change over time is recorded by an instrument to form a chill down Linear dispersion. The melting point is determined according to the temperature corresponding to the temperature platform in the Linear dispersion. The standard requires the accuracy and specifications of the required instruments, such as heating devices, chill down baths, thermometers, etc., and details the operation steps such as sample preparation, heating and chill down rate control. According to this standard, the melting point of petroleum wax can be accurately determined, which provides important parameters for the quality control and application of petroleum wax.