As a new pattern of navigation approach with the characteristics of high robustness, autonomous characteristics and anti-interference ability, polarization navigation attracts the attention of the experts to perform further researches. A relatively stable skylight polarization pattern exists in a certain time period at a specific place, which acts as the precondition for the completion of the polarization navigation. Therefore, the measurement of skylight polarization is of great importance to the polarization navigation. Various skylight polarization pattern measurement approaches have been performed in the past. However, disadvantages exist in the current measurement instruments, including time delay and non-synchronization. In this paper, a new image-based three-camera skylight polarization pattern measurement system is presented with its real-time and synchronous advantages. The main designing idea of the system is to equip the three cameras with three linear polarizers of different polarization directions, which could perform skylight image acquisition synchronously at the same time. Experiment with this system shows that it is able to obtain the stable skylight polarization pattern with the average time for measurement cycle 1.25s, significantly improving the acquisition time. Validation of the experimental results with theoretical result is also performed, proving the authenticity of measured data.