Abstract: The chronoamperometry at constant-potential under the condition of lamina flow has been suggested. The method is to measure the electrolytic current and time of the solution when its state changes from flow to stagnation and to calculate the coulomb. The electrolytic potential is controlled at the position of the polarographic limiting-current. The electrolytic cell is made small and thin in size and contains three electrodes: a Ag/AgCl for reference electrode,a gold ring for auxiliary electrode and a gold dish for indicator electrode.An equation that relates coulombs and concentrations of the solution has been given. The principle of quantitative analysis and experimental operations has also been described in the present paper. After the interference caused by capacity currect and unstability of the electrode were eliminated, the sensitivity of the method increased to the extent of 10^-7M. It has been proved experimentally that this method has several advantages, such as low noise, high resoluting power, stableness and good repro-ducibility. The advantages of stripping analysis were also shown obviouslywhen combined with chronoamperometry.