Abstract: A simple and new method for calculating charge distributions at ortho-, meta-and para-positions,δQ_o, δQ_mand δQ_p, in monosubstituted benzene molecules is presented. Several empirical rules to judge orientation effect in aromatic electrophilic substitution reactions are found. These are:1.when δQ_p/δQ_m>1 but △δQ<0, groups of this kind are ortho-and para-position directing with activation; 2. when δQ_p/δQ_m>l but △δQ>0, groups of this kind are ortho- and para-position directing with deactivation; 3. when δQ_p,/δQ_m<1 but △δQ>0, groups of this kind arc meta-position directing with deactivation.