Coupled with off-line extraction, a pre-column derivatization liquid chromatographic fluorescence detection (LC-FL) procedure was developed for the determination of atrazine and simazine in soil, crop and water samples. Concentrations in real samples were expected to be at or below the low ng/g level, which requires pre-concentration of analytes and improved detection. 4-(2-Phthalimidyl) benzoyl chloride (PIB-Cl) was used as a pre-column derivation reagent for high-performance liquid chromatography. The clean-up and second-time concentration procedures, which were indispensable in the conventional analytical methods for soil and crop analysis because of the complexity of the samples, were replaced by a derivatization reaction between PIB-Cl and the analytes. The fluorescent and ultraviolet characteristics of the derivatives were investigated. The derivatization reaction and chromatographic separation conditions were optimized systematically. Detection limits of 1.2 ng/g for atrazine and 1.1 ng/g for simazine were obtained with recoveries of 84-95% for environmental samples. On the basis of practical application to five soil and five crop samples, the LC-FL method was compared with the conventional GC-MS method.