The gadolinium-copper phase diagram has been compicted by X-ray diffraction and differential thermal analysis. The allotropic change in the GdCu6 phase was observed at 735℃.In this system there exist four intermetallic Compouds: GdCu, GdCu2, GdCu5 and GdCu6. The intermetallic compound GdCu5 melts congruently at 932℃. The intermetallic compounds GdCu, GdCu2 and GdCu6 are formed by peritectic reactions at 759℃, 870℃ and 884℃, respectively. Two eutectic reactions occur: at 32 at% Cu and 668℃, 92 at% Cu and 875℃. Neither Gd in Cu nor Cu in Gd Shows any detectable solid solubility.