Based on the theory of magnetic dipoles, the 3D characteristics of the magnetic potential energy of magnetic particles in a magnetic field were analyzed, and the interaction force formula between the magnetic particles was derived. Additionally, the Velocity Verlet algorithm was adopted to simulate the interaction of soft magnetic particles, which were compared against the observed 2D dynamic processes of magnetite particles. The observational results are largely consistent with the simulation, which considers both the magnetic dipole force and the viscous resistance that occurs during the interaction of soft magnetic particles. Nevertheless, significant difference exists between the 2D dynamic observation and the simulation for the interaction of magnetite particles. Three series of experiments and simulation show that all the magnetic particles are arranged in chain structures and orientated along the direction of the external magnetic field. Furthermore, the results show that the time required for magnetic particles to form magnetic chains is negatively correlated with the intensity of the magnetic field, and positively correlated with the viscosity of the chosen medium. (C) 2015 Elsevier Ltd. All rights reserved.