NiAl-Mo eutectic composites with two kinds of composition, 46.59Ni-45.61Al-7.8Mo and 44.86Ni-46.3Al-9.01Mo(at%), were prepared by directional solidification technology. The characteristics of solidification microstructure for the alloys at different withdrawing rates were studied. Results show that the microstructure of 46.59Ni-45.61Al-7.8Mo alloy was hypoeutectic at different withdrawing rates. The primary NiAl phase was dendritic; those initial dendrites disappeared gradually as their preferred growth direction did not coincide with the direction of heat transfer during the vertical directional solidification. With increase of the withdrawing rate, the dendrite arm spacing of NiAl phases was decreased little by little. For the 44.86Ni-46.3Al-9.01Mo alloy, eutectic microstructure of rod-like Mo phases inserted in NiAl matrix was formed at different withdrawing rates. With the increase of the withdrawing rate, both of the average spacing and the average diameter of the Mo phases decreased. When the withdrawing rate exceeded 14 mm/h, the continuous and regularly-ranged rod-like Mo-phase turned to irregular and discontinuous