Magnetic fluid is a colloidal liquid magnetic material formed by uniformly distributing ultrafine magnetic particles in the carrier liquid. It breaks the traditional form of solid magnetic materials and is a new type of material with both solid magnetism and liquid fluidity, with an extensive range of applications. At present, magnetic fluids have been applied in the medical field, and research has shown that magnetic fluids can be used to treat cancer cells, separate blood vessels and cells, targeted drug delivery, etc. In addition, magnetic fluids can also be applied in sealing, lubrication, and other aspects. Terahertz waves refer to frequencies ranging from 0.1 to 10 THz and wavelengths ranging from 30 to 3 000 μm electromagnetic radiation. Because the vibration and rotation modes of many biomolecules are in the terahertz frequency band, and the energy of terahertz waves is low, they will not damage the tested object. Therefore, terahertz waves can be used for non-destructive testing and are a safe and reliable measurement method. Microfluidic technology can be used to measure tiny amounts of liquid samples, with advantages such as simple operation, fast detection speed, and saving of measured samples. This study innovatively combines terahertz technology with microfluidic chip technology to study the terahertz characteristics of magnetic fluids at different magnetic fields and temperatures at different times. It was found that when a magnetic field was applied at different times, as time increased, the terahertz time-domain spectrum of the magnetic fluid shifted to the right. The intensity of the frequency-domain spectrum decreased. When different temperatures are applied, as the temperature increases, the time-domain spectrum also shifts to the right, and the transmission intensity decreases. It is preliminarily believed that the magnetic particles in the magnetic fluid undergo aggregation and directional arrangement under both external magnetic field and electric field conditions. With the extension of time, the particle spacing decreases, and it is approximately believed that the radius of the nanoparticles increases, making it difficult for terahertz waves to pass through and reduce their intensity. As the temperature increases, molecules thermal motion intensifies, and molecules vibration and rotation strengthen, making it difficult for terahertz waves to penetrate and thus reducing their intensity. Due to the lack of relevant reports on using terahertz to study the characteristics of magnetic fluids, this discovery provides a new method for exploring magnetic fluids. The study of terahertz characteristics of magnetic fluids under external magnetic fields can be applied to the medical field. These findings provide a new approach to applying terahertz technology in biomedicine and provide technical support for the in-depth application and research of magnetic fluids.