Only calibrating the response non-uniformity among three polarization channels of 0°, 60°, and 120° in the same waveband of a GF-5 satellite directional polarization camera (DPC) can make the accuracy requirement of polarization detection met. The wide field-of-view with DPC range of -50°--50° is divided into 15×15 sectional field-of-view and a high-accuracy two-dimensional turntable is used to adjust the position of each sectional field-of-view for aiming the integrating sphere reference light for imaging. The mosaic algorithm of the sectional field-of-view image data based on time stability is designed to obtain the mosaic images of the entire field-of-view. Furthermore, the logarithm enhancement method is used to detect the location and number of bad pixels in the mosaic images. The mosaic images are used to calculate the relative transmittance, low frequency relative transmittance, and high frequency relative transmittance of three polarization channels in the same waveband of DPC, and a calibration factor is provided for the calibration of DPC polarization channel response non-uniformity. The results show that the measurement uncertainty of DPC polarization channel response non-uniformity is superior to 0.67%. The proposed method provides a high-precision tool for calibrating the response non-uniformity among DPC polarization channels and for improving the analytical accuracy of polarization information.