Abstract: Wavelength calibration is an important step for CCD-spectrometers. The accuracy of the wavelength calibration will affect the precision of the measurement results. However, the accuracy of traditional wavelength calibration will be affected by instrument bandwidth and noise. The bandwidth of the instrument will generate the overlapping peaks in the calibration spectrum or cause the peak position shift of double peak. The noise will make inaccurate measurement of peak point. To solve this problem, a simple and accurate wavelength calibration method for CCD-spectrometer was proposed. The automated decomposition algorithm and Voigt line profile model were used to optimize the shape of the calibration spectrum and the precision value of the peak points of each calibration peak could be obtained. Using this method, the influence of bandwidth and noise could be eliminated, especially the overlap peaks could be decomposed into several single peaks, simultaneously, and the process of calibration was greatly simplified. Experiments based on USB4000 spectrometer with mercury-argon calibration light source were implemented. The results show that the proposed method could achieve higher accuracy and the calibration deviation is less than 0.1 nm. Therefore, it is recommended to use this method to calibrate the wavelength of the spectrometer.