The particle size distribution, specific surface area and circularity of cement particles are important parameters in cement processing. In order to realize the real-time monitoring of the above technical indicators, an on-line measurement system was developed based on the imaging method and the measurements of particle size distribution, specific surface area and circularity of cement particles were performed in the cement plant. The particle size distribution and specific surface area by the system were compared with the measured values by the laser particle sizer and the Blaine specific surface area analyzer, which indicates both are basically consistent. In addition, aiming at the problem of the lower limit of image measurement, the original results were fitted and corrected based on the Rosin-Rammler distribution function, which extends the lower limit of measurement of the image method and makes the measurement results more conformable with the actual situation, thus provides real-time data for industrial production.