The disturbance of gas chromatog. separation of prochloraz by copper was eliminated using 10% sodium polysulfide solution as the precipitant.Prochloraz was extracted by standard solution, and the pH value of organic solvent was controlled at about 7.5.Prochloraz in organic phase was analyzed by gas chromatog./FID (SE-54 column) with internal standard method.The relative standard deviation (RSD, %) was below 0.2%, the recovery was 99.83%, and the coefficient of variation was below 1.0%.The correlation coefficient was 0.9995.