Abstract: The kelp knots are the main product for exporting and earning foreign exchange in Chinese kelp culture provinces, but there are no mechanical processing devices. Therefore, the kelp knots are usually tied manually. Based on the principle of bionics, this paper offered an automatic knotting machine which could make the kelp forming a circle and passing through it to form a knot with the logic circuit. The test verified that this knotting machine was able to complete the operational requirements for kelp knotting accurately, which showed that this design was reasonable and feasible, and had the value of promotion and application after further optimization. It could also provide certain reference for the design and application of relevant knotting equipment.