A method of detecting a concentration of a target component by using a reference wavelength includes: defining a wavelength at which a light intensity is insensitive to the variation of the target component concentration as a reference wavelength for the target component; detecting spectra at both the reference wavelength and a further measuring wavelength; processing the spectrum detected at the further measuring wavelength, with the spectrum detected at the reference wavelength as an inner reference, to obtain a characteristic spectrum including specific information of the target component; building a calibration model between the characteristic spectrum and the concentration of the target component; and determining the concentration of the target component based on the calibration model.