To address the challenges of gas leakage monitoring in underground utility tunnels, where traditional single-variable threshold-based methods suffer from high misjudgment rates, significant response delays, and a lack of environmental factor integration (leading to frequent false positives and false negatives), this study proposes an intelligent gas leakage monitoring and early-warning system based on multivariate time-series data. Leveraging the bidirectional temporal feature extraction capability of Bidirectional Long Short-Term Memory (Bi-LSTM) networks, the system architecture is designed to incorporate critical environmental parameters associated with gas leakage. Multiple data acquisition terminal nodes periodically upload methane concentration, temperature, air pressure, and other environmental data to a centralized platform, enabling real-time monitoring of gas-related conditions across regional utility tunnels. For early-warning functionality, multivariate time-series datasets are constructed from sensor data collected by each node, and a Bi-LSTM model capable of processing multivariate inputs is trained to predict gas leakage events, triggering automated platform alerts. Experimental results demonstrate that the model achieves a training accuracy of 98.3% on an independent dataset, outperforming single-variable threshold methods by providing warnings 48.5 minutes earlier on average (empirical mean). Practical implementations confirm the system’s superior environmental adaptability and scalability for deployment in urban utility tunnel scenarios, significantly reducing leakage risks through timely and accurate hazard detection.