GB/T 17651.1 - 2021 mainly specifies the test device for the determination of combustion smoke density of cables or optical cables. The standard details the various types of devices suitable for this test, such as specially designed combustion boxes, and specifies their size, structure and material requirements to ensure a stable combustion environment. There are specifications for the optical path system, from the characteristics of Light sources to the accuracy of light detectors, to ensure the accuracy of luminous flux measurement. It also proposes performance indicators for auxiliary equipment such as air supply and smoke exhaust devices. Through the unified device standard, it provides a reliable hardware basis for the determination of smoke density in the subsequent parts of GB/T 17651, and helps the cable and optical cable industry to evaluate the impact of product combustion smoke.