This standard specifies a test method for evaluating the fire spread performance of flame-retardant wood-based materials. It measures core combustion performance parameters such as the fire spread index and weight loss rate by testing specimens under specific combustion conditions. This method is applicable to flame-retardant treated wood, wood-based panels, and other wood composite materials. The specialized testing instrument required for the test is a fire spread tester, the core components of which include a combustion chamber of specific dimensions, built-in gas burner tubes and electric heating elements, a specimen holder for fixing the samples, and a key device for monitoring temperature rise—thermocouples. During testing, the temperature changes in the flue are continuously measured by thermocouples and compared with a standard calibration curve, ultimately calculating the fire spread index, which quantifies the material's flame spread tendency.