The phase equilibria of the Co–Ni–Zr ternary system at 1 000 °C, 1 100 °C and 1 200 °C were experimentally investigated by means of back-scattered electron imaging, electron probe microanalysis and X-ray diffraction on the equilibrated ternary alloys. In this study, no ternary compound is found. The (αCo, Ni) phase region extends from the Ni-rich corner to the Co-rich corner with small solubility of Zr at three sections. At 1 000 °C and 1 100 °C, Ni 5 Zr, Co 2 Zr and Ni 10 Zr 7 phases have large solid solution ranges, but Ni 10 Zr 7 phase disappears at 1 200 °C. The Ni 7 Zr 2 , NiZr, Co 11 Zr 2 , Co 23 Zr 6 and CoZr phases exhibit nearly linear compounds in the studied sections, and have large composition ranges. Additionally, some differences in phase relationship exist among the above three isothermal sections.