Knotter is the key part of the rectangular baler. Most of knotters used in domestic are imported from abroad and the main types are D type knotter, C type knotter and C-D type knotter. ItÂÂs difficult to research the knotting process in the normal working state for the quick knotting action and the complicated mechanism. Therefore, it is of great significance to establish a test-bed which has features such as slow knotting-speed action and wide universality for researching the knotting process. This article mainly introduced the general structure design of the test-bed, the bales length adjustment and manual design of the knotter, the experiment of D type knotter, C type knotter and C-D type knotter manually or in normal operation. The experiment was made using the test-bed, the results showed the locking rate was 99.6%, which showed that the overall design project was feasible and laid foundation for further knotter research.