A rich variety of two-phase microstructures have been shown to form in the directionally solidified Pb-30wt.%Bi alloy. The selection of microstructure is shown to be depended upon the value of G/V (temperature gradient in the liquid divided by growth rate). The microstructure evolution is also discussed based on the competitive growth of different phase at various G/V ratios in directional solidification. Experimental results indicate that the primary a phase is the leading phase and grows with a dendritic/cellular microstructure while the peritectic b phase grows with cellular/planar microstructure in interdendritic/intercellular region at low G/V value. In contrast, competitive structures but not the discrete banded structure is present at high G/V ratio which makes the primary and secondary phase to grow with planar/cellular interface.