Abstract: Smashed potato sample was extracted ultrasonically with water, the filtrate was treated by dynamic liquid phase micro-extraction (DLPME) using n-octanol as extracting agent, to separate and enrich the 3 organophosphorus pesticides, i.e., dichloroas, methylparathion and parathion, which were then determined by GC. OV-1701 capillary column was used in GC separation and flame photometric detection was adopted in the determination. Ranges of linearity for the 3 organophosphorous pesticides were same between 2.0-50.0 μg·g-1, with values of detection limit (3S/N) of 0.20, 0.46, 0.42 μg·g-1 for methylparathion, parathion and dichlorovos respectively. Using potato samples as matrixes, values of recovery found by standard addition method were in the range of 90.6%-101% with RSD′s (n=7) in the range of 3.2%-5.6%.