The aberrant effects of different concentrations of potassium dichromate was studied by using Zea mays L. root tip cells. The micronucleus and chromosome aberration assay were conducted to determine the micronucleus frequencies and chromosome aberration frequencies of Zea mays L. root tip cells which induced by potassium dichromate. The result indicated that potassium dichromate could increase the micronucleus frequencies of Zea mays L. root tip cells. With certain range of concentration（0.0-25.0 mg/L） the frequencies of micronucleus was found to be increased with the increase of potassium dichromate concentration but beyond this range（25.0-100.0 mg/L） the frequencies of micronucleus decreased with further increase of potassium dichromate concentration. The potassium dichromate at different concentrations could increase the cell mitosis index. Besides, It also caused various types of chromosome aberration and the frequencies of chromosome aberration were always higher than that of the control group. The conclusion of this study was that potassium dichromate has obvious teratogenic effect on Zea mays L. root tip cells. In some degree the micronucleus frequencies of plant cells was able to show the grades of pollution of potassium dichromate in the environment.