The problem of computer modelling and visualization of low frequency electromagnetic fields is in the area of interest of such directions as education, research activity, medicine and industry. Visualization helps better understanding the influence of magnetic fields on various physical environments, and a clarifying the physical and mathematical models that are used. In industry visualization is often applied in the tools for non-destructive testing and in magnetic inspection systems. In medicine these fields are traditionally used in magnetotherapy, and at the moment computer modelling and visualization are often the only practical approach to the studying the influence magnetic fields on a living organism. In this work we demonstrate a computer tool both for modelling a magnetic field distribution and the motion of a charged particle in this field. The algorithms are implemented in a special environment Unity. That allows the combining calculations and visualization and results in considerable reducing run-time and the development of a flexible application that may be easily used by physicians. The results of experiments are given.