The growth behavior of Al3Ni intermetallic compounds (IMCs) during the directional solidification of Al-10 wt% Ni alloy was investigated by synchrotron radiography. Two main growth patterns of primary Al3Ni phase, I-like and V-like, appeared during solidification, and I-like Al3Ni phase grew faster than V-like phase, which can be explained by the minimum energy criterion. The growth of I-like phase can be divided into two stages and was mainly affected by undercooling and Ni concentration. We also found that V-like Al3Ni phase can evolve into M-like phase during solidification.