The melt of nonleaded free-cutting brass is modified by the electric pulse and the effects on the solidification structure and properties of Silicon Brass are studied with different Bi contents and under different pulse parameters. The results show that the varieties of Bi contents and pulse parameters have a greater impact on grain size and microstructure uniformity of the brass. After silicon brass with 0.5% Bi is modified by electric pulse, the Bi grain size is reduced to 5μm from 30μm, and its shape is changed into being granular from worm-like or long-strip-like, distributed more evenly in α phase and α phase boundary, and a few of which goes into the β phase matrix.