The accuracy of wavelength calibration is one of the important specifications for measuring a spectrometer. Because of its importance, the wavelength calibration of a Charge Coupled Device (CCD) array UV spectrometer is studied. A new wavelength calibration method containing noise deduction, spectrum peak location and wavelength fitting is given. To reduce the influence of dark noise on spectral signals, a method for deducting dark noise by using non-exposure pixels is proposed. To solve the problem of spectrum-peak drift, a spectrum-peak location method based on weight narrow-window difference is proposed. For the lacking of spectrum line of a single light source, a multiband wavelength fitting method is proposed. The experimental results show that the proposed method has its wavelength calibration accuracy less than 0.6 nm. Its calibration accuracy at key wavelength points is less than 0.01 nm. Because of the advantages of high calibration accuracy and low complexity etc, it can be used for the wavelength calibration of UV spectrometers.