Abstract: Ti51ZrNiCu filler alloy was used to study the reactive wetting process on TA1/TC4 heterogeneous interface. The interfacial microstructure of different surfaces was studied by scanning electron microscope(SEM), energy dispersive spectrometer(EDS) and wetting angle measuring instrument. And the influences of experiment parameters on interfacial microstructure and wettability were summarized. The filling experiment was finished to evaluate the wetting and spreading ability of TiZrNiCu on TA1/TC4 heterogeneous interface. The empirical equation of filling experiment was summarized. The empirical equation, h = 4000/a, was used to assess filling ability of TiZrNiCu on TA1/TC4 heterogeneous interface at 935 ℃ for 3 min. In this empirical equation, the unit of brazing gap a is μm, and the unit of climbing height h is mm.