This document specifies the classification, testing principle, testing device, performance test and testing report of the thermal insulation performance of the building curtain wall, which is applicable to the testing of the thermal insulation performance of the building curtain wall. A series of normative documents are cited as essential provisions, including standards for thermal insulation materials and terminology, steady-state thermal resistance measurement, general technical conditions for building curtain walls, etc. The testing principle is based on the steady-state heat transfer principle, and the calibration heat box method is used to detect the heat transfer coefficient of the building curtain wall.