Abstract: Gas chromatographs (GCs) play a crucial role in natural gas energy metering and trade settlement; however, conventional systems generally employ helium as both the carrier and valve-driving gas, resulting in high operational costs. To address this issue, a novel online GC analytical method based on carrier-gas splitting and multi-stream optimization is proposed. The method physically decouples the carrier gas and valve-driving functions by modifying the gas circuit and replacing helium with nitrogen or natural gas. Furthermore, a multi-stream sampling system is introduced, enabling a single GC unit to perform simultaneous online analyses of multiple gas sources and components. Experimental results indicate that under zero-grade nitrogen driving, valve actuation gas consumption is maintained at approximately 100 mL per cycle, while column and detector temperature stability are within ±0.3 °C. Field tests on EMERSON 570 and 370XA chromatographs confirm that the modified system meets the requirements of GB/T 13610 and JJG 1055 standards. This method substantially reduces helium consumption, operational costs, and equipment investment while maintaining analytical accuracy and stability, demonstrating significant economic benefits and strong potential for large-scale industrial applications in the natural gas sector.