Cobalt, nickel and their alloys are used as binders in cemented carbides because of their superior wetting and adhesion properties. Ti plays an important role in manufacturing of graded cemented carbides. Ni is the major constituent of nickel-based super alloys which can be strengthened by alloying Co, Ti and other elements. To facilitate the research and development of relevant materials, a knowledge of phase equilibria in the Co-Ni-Ti system is necessary. In this work, the phase diagram of this ternary system was experimentally investigated in full composition range and different temperatures. The liquidus projection was determined for the first time. Then thermodynamic assessment was conducted on the basis of current work and reliable data from the literature. A set of self-consistent parameters were obtained to describe the Gibbs energy of both stable and meta-stable phases. The calculated phase diagram can reproduce the experimental data well and help us understand microstructure evolution during solidification.