The Yilan-Yitong Fault Zone, a core part of the northern Tanlu Fault Zone, is a key seismogenic structure in Northeast Asia. Its Liaoning segment suffers from unclear surface distribution, insufficient late Quaternary activity evidence and lack of refined research based on optimized multi-source remote sensing data, which restricts regional seismic hazard assessment and major engineering safety layout. This study aimed to conduct fine detection and activity evaluation of this fault segment using high-resolution satellite data. We took GF-2 panchromatic and Sentinel-2 multispectral images as core data, compared four fusion algorithms (PCA, GS, HSV, Brovey) via qualitative and quantitative evaluation, and combined UAV remote sensing, field surveys of 28 key observation points and large-scale trench (25 m × 8 m) verification in Kaiyuan for systematic analysis. Results showed the PCA algorithm had the optimal comprehensive performance, suitable for fine geological interpretation. The fault was divided into three subsegments, with the Tieling-Kaiyuan segment showing distinct linear geomorphology and strong late Quaternary activity. The trench provides evidence suggestive of Holocene activity, and flower structures plus multi-phase faulting events reflected multistage activity characteristics, with preliminary identification of paleoseismic relics. This study verifies the application potential of domestic high-resolution satellites, fills the gap in refined activity research of the fault’s Liaoning segment, and provides high-precision scientific support for Liaoning’s seismic hazard assessment and major engineering safety layout.