The equivalent cireuit model ( ECM)is an important means to study the complex physical andchemical process of the electrochemical impedance measurement of solution, and it has important application inthe engineering technology research and development of the equipment such as the solution conductivitymeasurement instrument,The potassium chloride solution ( KCl) was selected as the research object , and theimpedanee spectrum of 0.01 mol/l, to 1 mol/L, KCl was measured using electrochemical work station andplatinum black parallel double electrodes, The Lima and Randles ECM were used to fit the measurement resultsrespectively and the accuracy of the two models were compared. Based on the fact that the physical andchemical mechanism of the solution is diflerent at different AC excitation signal frequencies ,the measurementresults are simulated at high and low frequencies respectively, to further improve the simulation accuracy , andthe high-frequeney ECM is raised based on the Lima ECM and Randles ECM. High frequency ECM was used tosimulate the conductivity of KCl solution with different concentrations at high frequeney , and the differences of ohysical and chemical processes in solution caused by different coneentrations were compared and analyzed.