The external thermal insulation composite system （ETICS） is crucial for improving building energy efficiency and ensuring building functionality. In recent years， issues such as cracking， hollowing， peeling， and high-altitude falling have occurred frequently， posing a significant threat to public safety. A systematic review was conducted on domestic and international research and engineering practice regarding diagnosis and treatment methods for detection， evaluation， and repair of building ETICS. In terms of detection， non-destructive testing techniques were categorized into four types based on their energy forms and physical mechanisms， namely optical， thermal， electromagnetic， and acoustic. The research progress of various non-destructive testing techniques and commonly used destructive testing techniques was systematically reviewed. A comparative analysis was conducted on the technical points， advantages and disadvantages， and applicable scenarios of various detection techniques. In terms of evaluation， the characteristics and progress of existing evaluation methods were summarized from three aspects： qualitative evaluation， quantitative evaluation， and comprehensive evaluation. In terms of repair， the current development status of existing repair methods was introduced from the perspectives of repair technology， repair materials， and repair strategies. Finally， the deficiencies in the research and engineering practice regarding diagnosis and treatment methods for building ETICS were analyzed， and future research directions were discussed.