The influencing factors and mechanisms of oxidative degradation of three organophosphorus pesticides (dichlorvos, methamidophos and phoxim) were studied by HPLC technique with a solid oxidant sodium percarbonate (SPC).The result showed that SPC had highly activity in degrading those organophosphorus pesticides.The most efficient degradation of pesticides occurred under base condition and the degradation rates also increased with time extension and temperature enhancement.The degradation of pesticides was expected to get even better results at a lower initial concentration.Furthermore, on the basis of the analytical results of intermediate products by NMR spectrometry, the degradation mechanisms were proposed for these pesticides.