The effect of ions on sonolytic degradation of two typical organophosphorus pesticides (parathion and dimethoate) is investigated. In experimental condition ranges, both the parathion and dimethoate degradation conform to pseudo firstorder kinetic model. With the increasing of ionic strength, the degradation rate of parathion and dimethoate increases at first then decreases. When the ionic strength is 0.01 mol, the degradation rate of parathion and dimethoate increase by 7.2% and 18.6% respectively. The effect of ionic strength on dimethoate degradation is more significant compared to parathion. The reducible cations Fe2+ and Mn2+ at level of 0.1 mM have an obvious catalytic effect on both parathion and dimethoate degradation, and the catalytic effect of Fe2+ is more obvious than Mn2+. The catalytic effect of Fe2+ and Mn2+ increases firstly but then decreases with the increase of the cations levels. The CO-3 , HCO-3, and Cl- at the level of 0.01M exhibit inhibitory effect on both parathion and dimethoate degradation, and their inhibition degrees follow the order of CO-3>HCO-3> Cl-. But only 1mM of Br- has an obvious catalytic effect both on parathion and dimethoate degradation, and the effect increases with the increasing Br- level.