In view of sorting perilla being high labor intensity, low efficiency by manual work and lacking automatic sorting system in China, a high efficiency system for sorting perilla was developed. The system was composed of hardware modules and software modules. The hardware modules included feeding unit, detecting unit, transporting unit, sorting unit, blanking unit, air supply system and control system. The maximum length of perilla’s blade was the most important and suitable parameter in sorting perilla according to its size. In order to carry out image processing and measure the maximum length of perilla’s blade, a high efficiency algorithm was developed based on morphological features of perilla. The algorithm consisted of target extraction, minimum circumscribed circle searching and result sorting. Based on the above hardware modules and the algorithm for measuring the maximum length of perilla’s blade, the software modules was developed. Experimental results showed that the processing time of single image was about 0.18s, the sorting speed was 4 pieces per second, the total average absolute error of the proposed system to measure the maximum length of perilla’s blade was about 0.157cm and the total sorting accuracy was 90.09%. The system realized the whole process of sorting perilla from feeding to blanking automatically with minimum destruction at a high speed and high accuracy, it provided technical support for later relevant research and development of perilla sorting system.