For researching the pattern of skylight polarization, a real-time measurement system which can capture images of different polarization direction at the same time was designed based on the analysis of existing measurement systems. Based on system light path simulation, the equipment was built and optimized. The error analysis and calibration was made for the equipment and the measuring accuracy was improved. The error of linear polarization degree is less than 1.6%, and error of polarization angle is less than ±0.32°. Outdoor experiments were carried out after calibration. In different bands, the results between the pattern of skylight polarization and Rayleigh model are significantly different. In 520 nm band, the data is close to Rayleigh model’s result.