Due to the increasing need for energy and the declining supply of fossil fuels, researchers have directed their studies on nuclear fusion. Nuclear fusion is a process in which two lighter nucleuses of an atom merge into one heavier nucleus, releasing large amounts of energy due to mass defect. To be able to use that reaction as an energy source, it is necessary to ensure conditions in which the reaction will take place continuously. That is exactly the task of nuclear fusion reactors, such as tokamaks. The concept of tokamak device is used in ITER, the most promising thermonuclear experimental reactor. Current diffusion equation (CDE) describes the current (or, equivalently, the magnetic field) diffusion through the plasma as a conductive medium. There are two ways to solve CDE. First one is FEM (Finite – Element Solution Method) and the second is analytical approach. Task of this paper is, using analytical approach for solving CDE, to determine poloidal magnetic flux for different plasma parameters. The first part of the task is to create a graph that contains poloidal magnetic flux in two arbitrary time moments using initial coefficients (a1, a2, a3, k and A). The second part of task is to change listed coefficients for the same time moments and compare new poloidal magnetic flux function with the initial function. From the obtained results it is clear that poloidal magnetic flux is strongest at magnetic axis. Magnetic axis is the limiting flux surface at the center of plasma. When we increase coefficients we get new poloidal magnetic flux function witch has steeper drop. That means new poloidal magnetic flux, for the same distance from magnetic axis, will be weaker than the initial flux. If we decrease coefficients we will get new poloidal magnetic flux function witch has milder decline. That means new flux, for the same distance from magnetic axis, will be stronger than the initial flux.