The influence on ion motion of magnetic turbulence observed in the Earth's magnetotail is investigated by numerical simulation. The magnetotail current sheet is modelled as a magnetic field reversal with a normal magnetic field component $B_n$, plus a three-dimensional spectrum of magnetic fluctuations $\delta B$ which represents the observed magnetic turbulence. The dawn-dusk electric field $E_y$ is also considered. A test particle simulation is performed using different values of $B_n$ and of the fluctuation level $\delta B/B_0$. In the relevant range of parameters, $B_n$ and $\delta B/B_0$ have opposite effects on the ion dynamics with the normal component causing the ions to be ejected from the current sheet and the fluctuations causing the ions tha have an increased residence time in the current sheet. These two parameters have opposite influence also on the current structure and on ion heating. We show that when the magnetic fluctuations are taken into account, the particle dynamics is deeply affected, giving rise to an increase in the cross tail transport, ion heating, and current sheet thickness. For strong enough turbulence, the current splits in two layers, in agreement with recent Cluster observations.