Objective: Through retrospective analysis of a case of occupational noise-induced hearing loss (NIHL) diagnosis and two-grade appraisal, this study explores the causes of inconsistency between diagnosis and appraisal conclusions, aiming to improve occupational health management. Methods: Data including occupational history, workplace noise exposure levels, pure-tone audiometry (PTA), and objective audiological tests were collected and analyzed. Results: Both municipal and provincial appraisals contradicted the initial diagnostic conclusion of “moderate occupational NIHL”. Conclusion: The diagnosis of occupational NIHL requires multidisciplinary expertise and is influenced by subjective factors. Appraisal institutions should adopt evidence-based approaches, integrate objective tests with PTA results, and comprehensively evaluate occupational exposure history to ensure scientific and impartial conclusions.