Abstract: A laboratory test program is conducted to investigate the effect of two different electrode spacings on the standard electro-osmotic drainage of clay. From the aspects of the volume of electro-osmotic drainage, rate of electro-osmotic drainage, energy consumption, effective voltage and contact resistance, two tests are compared to analyze the electro-osmotic characters of clay. The results show that decreasing the electrode spacing can improve the rate of drainage in certain time, lower the contact resistance and reduce the voltage drop, moreover, the rate of electro-osmotic drainage is proportional to the effective voltage, while the energy consumption is inversely proportional to the effective voltage. With the above studies, it is significant for us to understand and master the rules of standard electro-osmosis drainage of clay and it also lays a better basis on resolving the drainage problems of clay slope which is rich in water.