A rapid analysis method of herbicide bentazon and its metabolites (6-OH-bentazon and 8-OH-bentazon) in urine and blood has been developed. Automaticsolid phase extraction and HPLC/UV were used to extract and analyze pesticides. Therecoveries of bentazon, 6-OH-bentazon and 8-OH-bentazon in urine spiked with 2 mgof standards were 62.16±3.05%, 59.01±3.19%, and 109.93±0.01%, respectively. Inblood, the recoveries were 119.45±3.46%, 138.38±6.72%, and 131.02±3.86%,respectively. The detection limits of bentazon, 6-OH-bentazon and 8-OH-bentazon inurine are 0.047, 0.052, and 0.024 ppm, respectively. Gas chromatography-massspectrometry (GC-MS) was also used for further identification of bentazon. We haveused this method to extract and analyze bentazon in biological samples. In 89 samplesexamined, including 51 samples of urine, 30 samples of serum, 4 samples of blood,and 4 samples of renal water, we detected bentazon, 6-OH-bentazon and 8-OH-bentazon. The range of concentration was 0~1682.43 ppm.