GB/T 20643.1-2025 "Special Environmental Conditions - Environmental Test Methods - Part 1: General Principles" serves as a general guidance document for the series of standards, replacing the 2006 edition and refining the test system. It specifies the general requirements for both natural atmospheric exposure and artificial simulation tests, covering six special environments such as dry heat, plateau, and humid marine climates. The standard clarifies the observation and recording requirements for natural exposure tests and the principles for selecting methods in artificial simulation tests, while detailing data processing and result evaluation rules. It is applicable to the assessment of special environmental adaptability for various products, providing a unified technical foundation for subsequent specialized test methods and standardizing the entire testing process.