Abstract: For better resolution, enrichment and determinaiton of metribuzin residues in corn, a molecularly imprinted polymer with metribuzin as a template molecule synthesized by in situ polymerization was used as a solid-phase extraction sorbent for the on-line preconcentration and analysis of metribuzin residues in corn by liquid chromatography. The results showed that the molecularly imprinted polymer had significant molecularly imprinting effect and had high affinity and selectivity for metribuzin in water-containing system. Good linearity was obtained for metribuzin at the concentration of 0.01-0.50μg/mL with correlation coefficient of 0.9991. The detection limit (S/N=3) of the method for metribuzin was 1.8×10- 3μg/mL, the recoveries of metribuzin in corn at 0.01, 0.05 and 0.10 mg/kg were 80.9%- 94.5% and the relative standard deviations were less than 5.98%. The pretreatment procedure was simplified and the sensitivity was enhanced by using the method. The method was sensitive, reproducible, reliable, timesaving and no matrix interference. It could be used on the determination of metribuzin residues in corn.