A high performance liquid chromatography method had been established for the determination of malachite green and leucomalachite green in aquatic water. Malachite green and leucomalachite green were extracted with dichloromethane, then concentrated, and dissolved with acetonitrile. Samples were chromatographed using an acetonitrile-ammonium acetate buffer mobile phase on a C１8 column in line with a post column reactor filled with lead (IV) oxide and celite. The liner range was from 0.01μg•mL-1 to 1μg•mL-1 with r2 of 0.9999. The average recoveries of MG were 84.00%, 86.40%, 93.50%, and LMG were 74.00%, 89.00%, 91.80% when samples were spiked with MG and LMG of 0.1, 0.5, 1.0μg•mL-1 respectively. The detection limits of MG and LMG were 0.003μg•mL-1 and 0.004μg•mL-1 respectively. The RSDs were 4.278%-6.250% and 2.179%-6.757% respectively. The method is sensitive, accurate and suitable for the determination of trace malachite green and leucomalachite green in aquatic water. Key words: malachite green ; leucomalachite green; high performance liquid chromatography; aquatic water