The diffusion triple technique is an advanced and efficient method for determining ternary phase diagrams. Phase equilibria in the Nb-Ti-Si ternary system at 1 473 K was investigated using diffusion triple technique and electron microprobe analysis (EMPA). The experimental results indicated that seven diffu sion layers (viz. TiSi2, TiSi, Ti5Si4, Ti5Si3, Nb5Si3, NbSi2 and M3Si) exist in the Nb-Ti-Si ternary system at 1 473 K, and that no ternary compound was obser ved in this diffusion triple. A tentative isothermal section of this system at 1 473 K was constructed on the basis of experimental data. The isothermal section consists of seven three-phase regions.