Abstract: Pendimethalin is a selective herbicide, but its original medicine containing carcinogenic compounds - nitrosamines, which Pendimethalin in the content of the original drugs at home and abroad are strictly controlled. This paper first column chromatography with a rapid re-crystallization of the second method, separation and purification nitrosamines samples, and the establishment of a Pendimethalin the original spirit of micro-nitrosamines in the high-performance liquid chromatography quantitative analysis, Chromatography conditions are: water and acetonitrile (60:40) at a flow rate of 1 mL / min, with diode array detector, extracted at 240 nm. Nitrosamines and in the spirit of Pendimethalin linear regression equations were: y = 192459x + 89785, y = 803160x - 7E +07, the correlation coefficient were 0.9981,0.9872. Nitrosamines in the recovery to increase 98.6 percent to 100.1 percent, the detection limit of 0.65 ng / mL.