Covalent Organic Frameworks (COFs) are regarded as aclassofpromising Surface-Enhanced Raman Scattering (SERS) substrates, owing to their highly ordered porous structure, excellent molecular adsorption capacity, and structural stability have attracted widely attention. However, traditional COF materials lack plasmonic properties, making it difficult to achieve a high-intensity Raman enhancement effect, which limits their applicationin high-sensitivity detection. To address this issue, a novel ruthenium-based covalent was choosen. Organic framework composite material (Ru-COF) was designed and fabricated in this study for constructing high-performance SERS-active substrates. By directly incorporating ruthenium complexes into the COF skeleton, astable Ru–N/Ocovalent coordination structure was formed, which effectively improved the loading capacity and dispersibility of ruthenium, while significantly enhancing the electromagnetic field coupling strength and electron transfer capability ofthesubstrate.Compared with pure COFs, the Ru-COF substrate exhibited excellentSERS response performance in the detection of MethyleneBlue (MB) molecules. Specifically,it achieved a low limit ofdetection (LOD) down to10 ¹² mol·L ¹,alinearcorrelation coefficient (R²) ofno less than 0.99, and a high enhancement factor (EF) of up to 1.83×10¹. Additionally, the substrate showed good signal reproducibility(relative standard deviation, RSD < 5%) and retained over 90% o its initial signal intensity even after exposure to air for four months, demonstrating outstanding stability and durability. Further application studies indicated that the Ru-COF substrate could still realize stable detection of trace MB molecules in complex water samples, with the LOD remaining at the10¹² mol·L¹ level, along with excellent anti-ioninterference ability and signal consistency. This suggests that the substrate notonlyexhibits exceptional sensitivity and reproducibility under standard conditions but also holds potential for high-sensitivity quantitative detection in real environmental samples.The designstrategyofthismaterialprovidesanewresearchdirectionformetal-organic synergistically enhanced SERS systems and lays a crucial foundation for their practical applications in fields such as environmental pollutant detection,foodsafety analysis, and clinical diagnosis.