A rapid (less than 15 min), qualitative and semi-quantitative immunochromatography using colloidal gold-antibody probe was successfully developed and applied in determination of three kinds of organophosphorus pesticides (Fenitrothion, Parathion and Parathion-methyl) in water samples.The qualitative detection limit of the three kinds of pesticides was determined as 40, 20 and 20 ng ml-1 by using immunochromatography, respectively.In the semi-quantitative experiment, the detection results of chlorpyrifos-methyl were scanned by a membrane strip reader,and a detection curve representing the scanned data average was obtained.After conversion, it was observed that in the range of 10 ~ 2, 560 ng ml-1, the graph between logit (B/B0) and logarithm of concentration of the three pesticides were linear, from which, the regression equations (y=-1.7731x+3.299, R2=0.9972;y=-2.0286x+2.9948, R2=0.9785;y=-2.5134x+4.1917,R2=0.9738) were obtained.Meanwhile, the detection limits (I20) were calculated as 12, 13, 6 ng ml-1, respectively.In addition, other analog compounds were tested by using this assay and the results were regarded as negligible.The recoveries obtained by standard three pesticides addition to water samples were 74.56 % to 112.84 %, 81.84 % to 121.64 % and 77.16% to 132.48%,respectively.Overall, to our knowledge, this is the first report of qualitative and semi-quantitative detection of three kinds of pesticides by using one kind of immunochromatography.