Abstract: The abuse of novel phenylcyclohexylpyridine drugs poses a significant threat to societal safety. The novel psychoactive substance 2-methyl-deschloroketamine (2-MDCK), belonging to the phenylcyclohexylpyridine class, has recently surfaced as a new compound. However, there is a lack of understanding regarding its metabolic pathways and the identification of suitable biomarkers. In this study, a human liver microsomal model was established, and ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) technology was applied to investigate the in vitro metabolism and products of 2-MDCK. The results indicate that 2-MDCK undergoes various metabolic reactions, including dehydrogenation, deamination, hydroxylation, and demethylation, leading to the formation of eight metabolites. By conducting actual testing on hair samples from 2-MDCK abusers, the existence of six metabolites was confirmed. Comparing the metabolic products in the liver microsomal in vitro model, M3.1 and M4.1 were identified as biomarkers for 2-MDCK consumption. Five samples of abusers of 2-methyl-dechloroketamine were provided by the Anti-Drug Brigade of the Hangzhou Public Security Bureau. Negative hair samples were provided by laboratory volunteers, and all samples were obtained with the informed consent of the volunteers. These findings provide a scientific basis for the detection and identification of 2-MDCK and its metabolites, as well as crucial support for the study of the metabolic mechanisms of similar novel psychoactive substances in the phenylcyclohexylpyridine class. This research holds significant importance in addressing the issue of abuse of new psychoactive substances.