This standard specifies a general method for determining the melting point range of crystalline or powdered organic reagents using the capillary method. The method provides detailed specifications for the dimensions of the melting point tubes, sample pretreatment and filling procedures, key operations such as controlling the heating rate (e.g., 1.0 ± 0.1°C/min), and visual observation and recording of the initial and final melting temperatures. In addition to traditional manual setups (such as round-bottom flasks, glass test tubes, precision thermometers, etc.) that comply with the standard measurement principle, modern laboratories more commonly employ fully automatic melting point apparatuses and microscopic melting point apparatuses for testing. Fully automatic melting point apparatuses enable unattended automatic measurement and recording, while microscopic melting point apparatuses combine optical microscopy with precise temperature control technology, making them particularly suitable for observing subtle physical changes in samples during heating.