Abstract: The influence of electric pulse modification (EPM) process on the solidification structure of Sn-15% Pb alloy was experimentally investigated. It was shown that after the molten alloy was treated by electric pulse the solidification structure changed from dendrite shape to cellular shape, and the grains were obviously fined. The mechanism of the change in solidification structure by EPM was discussed. The results indicated that EPM process makes the liquid structure of the alloy change:The activity of Pb in the molten Sn-Pb alloy increases, the distribution coefficient tends to 1, the solute enrichment in front of the solid-liquid interface decreases, and the solute distribution changes. All these lead to the change of solidification structure from dendrite to cellular.