In the process of bioleaching of ore dump，a novel method for enhancing mass transfer of oxygen in leaching solution under electric field was put forward，and some experiments were performed to study its mechanism. The results showed that mass transfer could be enhanced by using electric field，and the effect of electric field on enhancing mass transfer was related to the strength of electric field and the properties of leaching solution. The higher the strength of electric field and the concentration of leaching solution，the more evident the effect of electric field. Mass transfer rate was affected by such factors as mass transfer coefficient，the size and movement of bubble，gas/liquid ratio and mass concentration of oxygen in gas phase. When the strength of electric field was 80 V·mm-1，total mass transfer coefficient would be 28. 2% higher than that without electric field.