In order to study the influence of outer scale and inner scale of atmospheric turbulence on the spot wander characteristics of Gaussian beam under strong fluctuation conditions, the variance expressions of beam wander of Gaussian beam in focusing and collimating conditions are derived firstly by using the modified von Karman spectrum, and verified by experimental data. Then, according to the derived beam wander expression, the characteristics of beam wander under different inner and outer scales are studied using numerical analysis method. The results show that the increase of outer scale will strengthen the effect of beam wander, while the change of inner scale has no significant effect on the characteristics of beam wander.