Abstract: The ion-selective electrode and isotope tracing technique arc applied in this study of metal ion transport in plant roots. The transport process in living plants can be followed continuously.With isotope tracing and ion-selective electrode technique, the influence of five crown ether dyes on transport process of the K⁺, Na⁺ and Ca⁺⁺ in wheat root system was studied.Preliminary investigation indicated that five crown ether dyes in very low concentrations (1×10^-3M) promoted the transport of potassium ion; on the other hand, the effect of 5 crown ethers on the absorption of sodium and calcium ion by wheat root system was irregular, some absorbed more and some less than the control group. The 4-(N, N-dimethyl-amino-benzene) -1- azo-4-benzo-15-crown-5 was the most effective among the five crown ether dyes.When the root system of single, young wheat was treated with dilute solution of a crown ether dye, 4-(N, N-dimethyl-amino-benzene)-l-azo-4-benzo-15-crown-5, the dye penetrated through the cell membranes of the roots and was absorbed on the sufaqe of micelles.