Linear array sensor S11639 is often used in mini-spectrometer for UV measurement. However, when the exposure volume of S11639 is relatively bigger, the non-linearity of the spectral response will appear. This nonlinear effect will affect the dynamic range of the mini-spectrometer, and therefore, nonlinear correction must be carried out. Photoelectric response of S11639 is measured with halogen tungsten lamp and deuterium lamp to find out the linear part between the exposure and the A/D conversion output, and straight line fitting of the data is made to obtain the factors of S11639 in the linear range. Based on it, the theoretical value in nonlinear range is got by extrapolation, and the difference between the theoretical value and the actual measurement value was calculated. The nonlinear correction of S11639 is realized by polynomial fitting with the least square method. At the same time, compared with the experimental results, the error causes of the experimental data are analyzed, and the experiment is provided for better utilization of mini-spectrometer based on S11639 for photoelectric de-tection in the full dynamic range.