In this study, the adventitious root of Panax quinquefolium L. was used as the material. The simulated drought stress was pretreated with 10% PEG-6000, and then exogenous salicylic acid (SA) at different concentrations (0, 10, 40, and 80 μmol·L-1) were added to treat 2, 4, 6 and 8 days, respectively. Then, the activity of antioxidant enzymes, the content of osmotic regulators, the accumulation of total flavonoids, total saponins, monomer saponins Rb1 and Re, gene expression of two bHLH transcription factors and 6 key enzymes in the ginsenosides biosynthetic pathway in adventitious roots of P. quinquefolium were detected. These results were used to explore the regulatory mechanism of exogenous SA in response to simulated drought stress in P. quinquefolium. The results showed that: (1) The activities of catalase (CAT) and peroxidase (POD) both peaked when 80 μmol·L-1 of SA was treated for 4 days. The content of free proline reached the peak at 4 days after 80 μmol·L-1 of SA treatment, and the content of malondialdehyde (MDA) reached the peak at 6 days after 40 μmol·L-1 of SA treatment. (2) The content of total flavonoids reached the maximum value when 80 μmol·L-1 of SA was treated for 6 days, and the content of total saponins and monomeric saponins Re reached the maximum value when treated with 40 μmol·L-1 of SA for 8 days, the content of monomeric saponin Rb1 reached the maximum value at the 6 days of 80 μmol·L-1 of SA treatment. (3) The expression levels of HMGR and DS genes were increased by more than 3 times on the second day after 40 μmol·L-1 of SA treatment, and the gene expressions of Pq-CYP6H, Pq-D12H, Pq-3-O-UGT1 and Pq-bHLH25 The amount was more than doubled after SA treatment. These experimental results showed that the appropriate concentration of exogenous SA could improve the growth state indicators of adventitious roots of P. quinquefolium under drought stress, and increase the content of active ingredients and the expression of related genes.