Part 2 of GB/T 25206.2 - 2010 describes the large-chamber method for testing the combustion performance of composite sandwich panels in buildings. This standard describes the principle of large-chamber testing and specifies the construction requirements of large-scale combustion test devices, including space dimensions, ventilating systems, etc. It details the installation and layout of composite sandwich panel samples, standardizes the test process, such as ignition source setting, combustion time control, and monitors the temperature and smoke spread during combustion. Through this standard, it can comprehensively evaluate the combustion performance of composite sandwich panels in simulated building spaces, provide a basis for the selection of safe materials in the construction industry, and improve the level of building fire safety.