High spectral analysis sensitivity can be achieved with orthogonal dual-wavelength dual-pulse laser-ablation laser-induced breakdown spectroscopy under minimal sample ablation. Therefore, the contradiction between spatial resolution and analytical sensitivity existed in single-pulse laser-induced breakdown spectroscopy can be resolved fundamentally in this technique. In order to eliminate the influence of different experimental parameters to the signal intensities and final results of quantitative analysis, the correlation between copper atomic emission and silver atomic emission was studied experimentally in this technique for silver jewellery samples. It was demonstrated that the intensity of atomic emission of copper at 324.75 nm and that of silver at 328.07 nm was linearly correlated with high correlation coefficient. Therefore, it was possible to eliminate the influence of different experimental parameters, such as geometrical arrangement and pulse energy of the ablation laser to the signal of copper atomic emission by selecting 328.07 nm line of silver as internal standard. A quantitative analysis of copper impurity in silver jewellery can be realized by using orthogonal dual-wavelength dual-pulse laser-ablation laser-induced breakdown spectroscopy. A calibration curve of copper was successfully built based on internal standard method while selecting 328.07 nm line of silver as internal standard. The limit of detection of copper in silver matrix was determined to be 44 ppm in this technique when the crater’s diameter was about 17 μm under current experimental condition.