The monochromators, which are able to separate a specific wavelength light from a complex spectrum and a continuous spectrum light source, have been widely used in optical measurements. As one crucial specification, wavelength accuracy has always been a research theme for monochromator users around the world. When the monochromator is utilized for calibrating the wavelength in the ultraviolet, visible, and near-infrared regions, low-pressure discharged lamps, such as mercury lamps, are usually employed to obtain wavelength deviations at certain wavelength points of atomic emission lines of lamps,which are well-known recognized. For the requirement of monochromator wavelength calibration, a light path based on the low-pressure discharged lamp method was constructed. Three strong radiation flux lines of the mercury lamps were selected and tested,whose wavelength values were 365.015 nm, 435.833 nm, and 546.075 nm. Meanwhile a new method based on continuous spectrum light source and Fourier transform spectrometer was proposed and light path was also built. Near the wavelength value points of the selected atomic emission lines of mercury lamp, a measurement experiment was performed both on the same monochromator and the same experimental conditions, and the wavelength deviation values of the monochromator was obtained. The consistency of the two methods was good, and the best repeatability error was better than 0.005nm. The work of this article is of positive for those measurement laboratories to select suitable approach to perform their monochromators wavelength calibrations.