This document describes in detail the Measuring method of Thermal conductivity of impermeable graphite materials. It is suitable for the measurement of Thermal conductivity of impermeable graphite materials in the range of 20 ° C to 40 ° C by comparative method at room temperature, and is suitable for impermeable graphite materials with Thermal conductivity less than or equal to 250W/(m · K). The normative reference document includes HG/T2370 standard on technical conditions of impermeable graphite chemical equipment. The document does not involve specific terms and definitions. The principle part describes the basic principle of measurement. Thermal conductivity of the test sample is calculated by drawing the U-lambda/h Linear dispersion diagram. Measuring method ensures accurate measurement of the Thermal conductivity of impermeable graphite materials and provides reliable reference data for materials in practical applications.