Abstract: Red ginseng is one of the important export products in China. Top grade red ginseng is packed in small packet in the world market. In small packet there must be a certain number of pieces of red ginseng and certain weight.The packing process is called "Weight-grouping". This grouping machine is an automatic machine for grouping red ginseng. The output of the machine is 30kg / h and its accuracy is (600g)+3g .The operating process of the red ginseng grouping machine is introduced and. an intel MCS-51 one chip microcmputer-based real-time control system using interrupt mode is discussed in detail.Combining with grouping method the functions of the system software are described.Digital simulation is used for assisting to determine the design parameters of the grouping machine and to estimate its performances.A number of real experiments to the grouping machine has shown that the results of real experiments coincide with the results of digital simulation. This means the red ginseng grouping machine is satisfacory with design requirements to its output and weighing accuracy.