Homocysteine is a sulfur-containing amino acid, which is an important intermediate product produced during the metabolism of methionine and cysteine. High concentration of homocysteine in human blood or urine will significantly increase the risk of cardiovascular disease, alzheimer′s disease, bone fracture and other diseases. Based on terahertz time domain spectroscopy (THz-TDS), a method of concentration, enrichment and drying was proposed for the detection of homocysteine in liquid state. The THz absorption spectra of homocysteine at different concentrations were measured effectively. Compared with the results of Raman spectroscopy, the accuracy of terahertz detection was three times higher than that of Raman spectroscopy. The results were of great significance for the accurate and rapid diagnosis of homocysteine-related diseases in clinical medicine.