Abstract: This study investigates common failures in distribution transformers, identifies their root causes, and proposes effective troubleshooting methods and preventive measures based on field investigations. The research adopts a combined approach of theoretical analysis and case studies. First, it categorizes the main failure types of distribution transformers, then analyzes the causes of various failures, and finally details the fault diagnosis and troubleshooting processes through specific cases. This work provides both practical guidance for distribution transformer failure diagnosis and troubleshooting, and a theoretical basis for enhancing operational reliability and extending service life.