As metro construction progresses, the automatic ticketing system demands higher standards for station infrastructure. Taking Xi’an Metro Line 15 as an example, this paper examines the construction technology of waterproof trench for the automatic ticketing system, and proposes a sectional modular prefabrication method. Results demonstrate that the use of advanced waterproof materials and innovative techniques significantly enhances waterproofing performance and construction efficiency, ensuring the long-term stable operation of the system.