The surface-enhanced Raman spectroscopy technology has specific recognition of molecules and rapid non-destructive detection capabilities, making it great potential in drug detection. In this study, drug detection research based on novel metal/titanium nitride composite substrate as SERS active substrate was carried out. Due to the synergy between the novel metal and titanium nitride, the composite substrate has high SERS performance, providing a drug detection method based on SERS technology. Electrochemical deposition and self-assembly methods were used to prepare novel metal/titanium nitride composite film. There are three kinds of phases: face-centered cubic crystal TiN, metal Au and Ag in the composite film. The electron microscopy showed that metal Au and Ag particles with a mean particle size of 90 and 50 nm were evenly distributed on TIN film's surface. For this reason, the characteristic plasmon resonance absorption peaks of the novel metal gold and silver nanoparticles and TiN thin film appeared in the ultraviolet-visible absorption spectra of the thin film. Using the composite film as the SERS substrate, Raman detection was performed on the nicotinic acid solution. The results show that the novel metal/titanium nitride composite film has a significant SERS effect. The logarithm of the Raman signal intensity and nicotinic acid concentration at 1 033 cm^-1 indicated a certain linear relationship between the two, the linear correlation coefficient was 0.969, and the minimum detection concentration of nicotinic acid was 10^-5 mol·L^-1. This is due to the effect of charge transfer and the enhancement of the electromagnetic field caused by the surface plasmon resonance between the particles of TiN, Au and Ag. It was also found that nicotinic acid was vertically adsorbed on the novel metal/titanium nitride substrate's surface through the COO^- group. When in an acidic environment, the protonation of nicotinic acid N atom mainly existed in cation N⁺H(Ⅰ). In an alkaline environment, it mainly existed in the form of anion COO^-(Ⅲ). In addition, for the illegal addition of nicotinic acid in the gypenoside solution, the lowest Raman detection concentration of the composite substrate is 10^-5 mol·L^-1, which provides a new way for the rapid detection of illegally added drugs on site.