The switch-losses of one Q-switch, two Q-switches in acousto-field perpendicular or parallel are analyzed. According to the theory of acousto-optic (AO) interaction, the formulas of diffraction loss of two AO Q-switches, which acousto-field are perpendicular or parallel one another, in Raman-Nath diffraction are derived. The power divider for ensuring two AO Q-switch synchronization and effective power driving is designed. The calculation results are satisfied with Nd∶YAG laser experimental results. It is shown that two AO Q-switches, which acousto-field are perpendicular each other, switch-loss is nearly three times large than one AO Q-switch, one time large than the two AO Q-switches which acousto-field are parallel.