The model of liquidphase of ZA27 cast alloy was set up in terms of the molecul ar dynamics simulation. The atomic structural models of the α phaseliquid int erf ace and the grain boundary of α phase with the coincidencesite lattice were c on structed by computer programming. The environmentsensitive embedding energy (E S E) of rare earth (or iron) atom in grain, on grain boundary and on α phaseliq uid interface was calculated by Recursion method. The bond order integrals (BOI) be tween Fe, RE atom and Al were also computed. The results show that RE and iron e lements are more stable on the α phaseliquid interface than in grain, which e xpl ains the fact of very small solid solubility of RE and iron elements in α phase , and the enrichment of RE and iron elements in the solid-liquid growth front whe n solidifying. This leads to the segregation of RE and iron atoms on the grain b oundaries and the formation of the complicated REcompounds.