The effect of the liquid-liquid structure transition(L-LST) on the solidification behaviors and morphologies of Sn-Bi alloys was studied further. The results show that the undercooling of the primary and eutectic phase increases and the microstructure becomes finer after solidifying from the melt experiencing the L-LST. In the meantime, in hypoeutectic alloy, when solidifying from the melt experiencing the L-LST, the morphology of primary phase changes from the fir-tree crystal into the equiaxed crystal, and less primary phase and more eutectic structure are observed. Moreover, in eutectic alloy, the spacing of eutectic phase decreases markedly. These investigations would be beneficial to further exploration of the correlation between the melt structure and the micro mechanism of solidification.