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In this paper, a self-assembly method was used to prepare gold nanorod composites, and a seed-growth method was used to adjust the amount of AgNO3 solution, enabling the preparation of gold nanorods with different aspect ratios. AuNRs@SiO2 nanocomposite particles were then prepared by using the Stöber method to coat the gold nanorod surface with silica. Transmission electron microscopy showed that the maximum aspect ratio of the gold nanorods was 4.53, which was achieved using 2 mL of 10 mM AgNO3 solution. The Raman-scattering intensity of the gold nanorods was studied using rhodamine 6G, thiram, melamine, and piroxicam, and detection limits of 10−8 M, 10−5 M, and 10−3 M were, respectively, achieved. As a substrate, these gold nanorods showed good repeatability and reproducibility, and trace detection was successfully achieved. A transmission electron microscopy analysis shows that the SiO2 shell became thicker with increasing tetraethyl orthosilicate addition. Using AuNRs@SiO2 as the base and R6G, thiram, and piroxicam as the probes, measurable detection limits of 10−9 M, 10−6 M, and 10−5 M were achieved, and this composite also showed excellent repeatability and reproducibility. [ABSTRACT FROM AUTHOR]