The effects of the Electrical Double Layer (EDL) on the liquid mean flow and the flow stability in microchannels are investigated by solving the Poisson-Boltzmann equation.The models of the traditional streaming Electrical Current Balance (ECB) and the newly introduced streaming Electrical Current Density Balance (ECDB) are applied to determine the electrical streaming current.The numerical results show that the electrical streaming current backflow in the ECB model near the wall can be removed by using the ECDB model,which is suitable to study the effects of the EDL on the mean flow and the flow stability in microchannels.The flow is found more unstable if the ECDB model is applied.