This standard is a technical specification for the quality assessment of recycled polystyrene (PS) and its impact-resistant variant (PS-I) pellet products. It establishes a comprehensive evaluation framework for mechanically recycled PS pellets, covering evaluation principles, specific content, assessment methods, and indicator systems. The standard sets evaluation indicators across multiple dimensions, including environmental and energy attributes, quality attributes, process management, and traceability, and specifies corresponding weights and verification methods. During the evaluation process, material performance testing is involved, such as using a gas chromatograph (GC) to assess residual styrene monomer content. Additionally, the industry widely employs melt flow indexers (MFR) to determine melt flow rates and universal material testing machines to evaluate mechanical properties when assessing the fundamental performance of recycled plastics. This standard aims to provide a unified and quantitative technical basis for the quality assessment of recycled polystyrene products, supporting their high-value applications and the development of a circular economy.