Individualized intravenous drug therapy imposes higher demands on the rapid and precise detection of drug components, especially as the identification of trace substances in complex matrices remains challenging. This study proposes a frequency-encoded, multi-wavelength detection system based on near-infrared spectroscopy, which mitigates water-induced spectral overlap and overcomes the limitations of single-wavelength lasers in solute identification and quantification. The system independently encodes eight groups of LD lasers within the range of 850 nm to 1 550 nm, and combines phase-locked amplifier algorithms for signal demodulation, effectively suppressing interference between wavelengths and improving signal accuracy and response speed. It integrates a high-sensitivity InGaAs array detector, capable of capturing the absorption features of C—N (1 380~1 430 nm) and N—H (1 500~2 100 nm). By establishing a spectral-to-concentration mapping model using neural networks, the detection time is reduced to less than 2 seconds, significantly improving efficiency. Experimental results show that in hydrochloride ambroxol (0.1~2 mg/mL) and biapenem (1~5 mg/mL) solutions, the concentration detection error is controlled at ≤5% (n=20), outperforming traditional HPLC methods (5%~8%). These results demonstrate the system′s potential in rapid drug component detection and individualized drug monitoring, with broad application prospects.