Abstract: The separation of silicon from alloy melt, and the recovery and reuse of alloy elements are key issues limiting the further application of Si-Al alloy solidification refining process. The temperature gradient zone melting method was used for the growth of bulk silicon in Si-Al alloy. By introducing a single crystal silicon substrate at the bottom of the alloy melt, the influence on the morphology of bulk silicon growth and impurity distribution was studied. The results show that the addition of a single crystal silicon substrate reduces the temperature gradient of the alloy melt, bulk silicon grows up with a straight interface, and the growth rate is significantly slower. When the temperature gradient is 2.4 K/mm and the growth time is 240min, the growth rate of bulk silicon decreases from 0.108 μm/s on the graphite crucible to 0.075 μm/s on the Si（100）substrate. At the same temperature gradient and growth time, the growth rate of bulk silicon on the Si（100） substrate is significantly faster than that of the Si（111） substrate. The single-crystal silicon substrate plays as seed crystal during bulk silicon growth.