The dynamic viscosity of pure In, In-1%Sb (mass fraction, so as the follows) alloy, In-55%Sb hypoeutectic alloyand In-69.5%Sb eutectic alloy was measured by using a torsional oscillation viscometer at different temperatures above liq-uidus. The experimental results show that the viscosity of these melts decreases with increasing temperature. The anomalouschange of viscosity occurs at about 430 and 470℃ in pure In melt. The variation of viscosity with temperature well meetsexponential correlation and no anomalous change occurs in measured temperature range in the In-1%Sb alloy melt. A tran-sition occurs at about 800℃ in both of In-55%Sb and In-69.5%Sb alloy melts. The sudden change of viscosity suggests thestructure change of melts. DSC (differential scanning calorimetry) curves of In-1%Sb alloy during heating and cooling weremeasured, and the results show that no structural variation in In-1%Sb alloy melt was testified further. In addition, the vis-cosity of In melt decreases with the addition of 1%Sb.