Under the transition toward low-carbon energy systems, natural gas transportation has attracted increasing attention with respect to transportation safety, operational coordination, and intelligent decision-making. Based on 1,687 publications retrieved from the Web of Science Core Collection database between 2008 and 2025, we conducted a bibliometric and knowledge graph analysis of natural gas transportation research using CiteSpace. Keyword co-occurrence analysis, cluster analysis, and temporal evolution analysis were employed to examine the knowledge structure, research hotspots, and evolutionary characteristics of the field. The results indicate that natural gas transportation research has gradually evolved into three major research streams: transportation risk analysis, coordinated operation and scheduling, and intelligent optimization. Early studies mainly focused on engineering-oriented safety analysis, while recent research has increasingly emphasized integrated energy coordination, uncertainty-aware decision-making, and intelligent transportation optimization under complex energy environments. Risk-related research has expanded from traditional accident investigation to quantitative risk assessment and risk propagation analysis. Coordinated operation research increasingly focuses on integrated energy systems and operational scheduling under uncertainty. Intelligent optimization research has developed rapidly in routing optimization, intelligent algorithms, and dynamic decision-making methods. Despite the rapid growth of these research streams, their integration remains limited. In particular, the interaction between transportation risk analysis and intelligent optimization has not been sufficiently incorporated into existing transportation decision-making frameworks. Future research should further integrate risk analysis, intelligent optimization, and real-time transportation decision-making to support the low-carbon energy transition.