Abstract: The ultrastructures of root meristematic cells changed when wheat roots were incubated in two kinds of concentrations of colchicine for different periods. With germinating at higher concentration and longer times, obvious ultrastructural changes were observed that nuclei were gradually getting smaller and the shape became irregular;rough endoplastic reticula stacked;the number of preplastid and microbody was reduced and that of anlylopast was increased; the column of vacuole and intercellular space increased too. The cell wall was thickened randomly and so on. Reasons for the changes were discussed. The characteristics indicate that the meristematic cells treated with colchicine in various conditions move into the states of differentiation cell.