Molecular communication is a novel method of communication that utilises nano-engineering and bio-engineering to enable temporary communication in harsh environments. As nano-technology and bio-engineering continue to advance, the feasibility of molecular communication is constantly improving. This paper examines the feasibility of using magnetic nanomaterials as information carriers for medium-distance transmission driven by magnetic field force, based on the existing molecular communication theory of diffuse channel. The study compares the two situations with and without relay. After conducting derivation and simulation verification, it can be concluded that the transmission rate and bit error rate data results are excellent when under the influence of magnetic field force drive. Additionally, the molecular communication system with relay is significantly more effective than the system without relay.