To explore the mechanism of phenylpropane metabolism in adapting to salt stress of L. barbarum. In this study, L. barbarum treated with different concentrations of NaCl (0, 100, 200, 300 mmol/L NaCl) was used as the research object. High-throughput sequencing technology and qRT-PCR were used to detect and analyze the differential expression of genes related to phenylpropane metabolism of L. barbarum under salt stress. Meanwhile, the activities of key enzymes and the contents of related substances were determined. The results showed as follows: (1) A total of 58 genes related to phenylpropane metabolism were differentially expressed under different concentrations of NaCl, and most of the genes were up-regulated or unchanged with the increase of salt stress. (2) With the increase of NaCl concentration, the activities of antioxidant enzymes SOD, POD and CAT in the leaves of L. barbarum decreased, while the contents of phenols, flavonoids and lignin were significantly accumulated under 100 mmol/L NaCl treatment. The results showed that L. barbarum could regulate the up-regulated expression of genes related to phenylpropane metabolism, increase the synthesis of phenols, flavonoids and lignin, and adapt to salt stress by clearing excessive ROS and improving cell wall strength. The concentration of NaCl that L. barbarum can tolerate is between 100 and 200 mmol/L. The results of this study provide theoretical basis for the cultivation and production of L. barbarum and the further analysis of the salt tolerance mechanism of L. barbarum.