S11639 is often used in mini-spectrometer for UV measurement. Ideally, each pixel of S11639, in the whole dynamic range, has good linearity between the amount of incident light and signal charge produced by photoelectric conver-sion. However, when the exposure of S11639 is bigger, the nonlinearity of S11639 photoelectric response will appear. The nonlinearity of S11639 is related to its structure, because sharing and diffusion of the pixel potential wells occur in the photosensitive area, and the charge interaction enhances more with the increase of the exposure, and even leads to charge overflow. So the more the exposure, the worse the linearity of S11639. The nonlinearity of the S11639 photoelectric response affects the dynamic range of the spectrometer. S11639 is applied in mini-spectrometer which has its own light dispersion system. Halogen tungsten lamp and deuterium lamp are compensated to light from the ultraviolet to the near infrared range of 215 nm~2500 nm. The light is injected through the optical fiber to spectrom-eter with this light source. The composite light passing asymmetric C-T optical system is decomposed into mono-chromatic light which is shined on the surface of S11639. The signal is amplified linearly and converted by A/D converter, and the output of A/D conversion is a function of the exposure. Photoelectric response of S11639 is measured to find out the relations between the exposure and the A/D conversion output in the multi wavelength po-sitions of S11639. The conclusion is described below: If the A/D initial output values are the same in different wavelength positions by adjusting the light intensity, the integral time is changed at the same step, and the changes of A/D output value are still the same, so only a photoelectric response curve is measured at one wavelength position, which is suitable for other wavelengths. By changing the integration time of the spectrometer at one wavelength po-sition, the exposure of S11639 is changed, and the value of the A/D conversion is obtained. Straight line fitting of the data is made to obtain the factors of S11639 in the linear range of one wavelength position. Extrapolating from the linear part will reach the theoretical values in nonlinear range, and we can calculate the differences between the ac-tual measurement values and the theoretical values. The polynomial fitting with least squares method realizes the nonlinear correction of S11639 at one wavelength position. Since the coefficients of the linear fitting are the same at different wavelengths, they can be applied to nonlinear correction at other wavelengths. 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 detection in the full dynamic range.