Abstract <p>During magnetospheric perturbations a relatively thin current sheet with thickness about several proton gyroradii forms in the Earth’s magnetotail. In a framework of the kinetic model describing current sheet thinning in the magnetotail, the processes of its formation are investigated depending on the normal magnetic field magnitude which affects both the current sheet structure and particle dynamics within it. The critical value of the ratio of the normal to tangential components magnitudes at current sheet edges is determined above which the formation of a stationary thin current sheet does not occur. The reason for this is the high density of trapped plasma particles around the sheet, which contribute to its magnetotail structure and finally lead to its destruction. It is shown that this ratio can be the important factor influencing quasi-equilibrium state of magnetotail current sheet as a whole and determining the characteristic parameter range at which the formation of a long-lived current structure with small thickness is possible.</p>