A facile method based on capillarity-assisted assembly is used to fabricate high-performance surface-enhanced Raman scattering (SERS) substrates employing clean Au nanoparticles (NPs). This method is better than micro-channel way because the former may supply large-area uniform assembly and overcome the uneven radial distribution. Such densely-arranged assembly of Au NPs exhibits high reproducibility and large Raman enhancement factors of 3 × 1010, arising from strong electromagnetic field coupling induced by adjacent Au NPs. The spot-to-spot SERS signals show that the relative standard deviation (RSD) in the intensity of the main Raman vibration modes (1310, 1361, 1509, 1650 cm−1) of Rhodamine 6G at a concentration of 1 × 10−10M are consistently less than 20%, demonstrating good spatial uniformity and reproducibility. The SERS signals of sudan dye at a 1 × 10−8M concentration also shows high reproducibility with a low RSD of <20%. Further, the assembly substrate is stable, retaining excellent uniformity and sensitivity after storage for months. This assembly strategy integrating the advantages of low-cost production, high sensitivity, and reproducibility would significantly facilitate practical SERS detection.