Abstract: The coastal area of Qinhuangdao has a typical humid climate, with high moisture levels and concentrated rainfall in summer. In a 10 kV distribution room, defects in cable trench sealing, insufficient ventilation, and poor drainage cause severe water accumulation and moisture buildup. These problems result in equipment corrosion, reduced cable insulation performance, and frequent faults. This paper analyzes the causes and hazards of moisture accumulation in cable trenches and proposes a comprehensive treatment scheme integrating drainage, ventilation, and intelligent control. The application results show that the temperature and humidity in the cable trench are controlled within reasonable ranges, and the moisture problem is effectively solved. This study provides a practical reference for moisture proofing and dehumidification treatment of cable trenches in similar distribution rooms in coastal areas.