Legal analysis: The coal mining specialty of safety and quality standardization coal mine is divided into three grades, and the percentage system is adopted, that is, the first grade score is above 90, the second grade score is above 80, and the third grade score is above 70.

Legal basis: "Standard for Standardization of Coal Mine Safety and Quality and Measures for Assessment and Rating" Article 1 The coal mining major of coal mine with standardized safety and quality is divided into three grades, which are scored with a percentage system, that is, the first grade score is above 90, the second grade score is above 80, and the third grade score is above 70.