Abstract: The wetting and spreading behavior of molten AgCuTi on the surface of TiNi alloy was investigated using molecular dynamics simulation method. We investigated the wetting behavior of AgCuTi filler metal on the surfaces of single crystal and polycrystalline TiNi alloys at different temperatures of 1073 K, 1123 K, 1173 K, and 1223 K. By analyzing the density distribution and simulating the wetting spreading image of equilibrium state, it was found that the increase in temperature has a significant promotion on the wetting process. No obvious dissolution reaction was observed during the wetting process, but instead a precursor film dominated by Ag was formed. As the temperature increased, a small amount of Cu and Ti diffused into the TiNi matrix in the melted AgCuTi, and a small amount of Ti in the matrix also diffused into the brazing material. By analyzing the mean square displacement, it was found that the formation area of the precursor film increased correspondingly with the increase of temperature. The wetting and spreading of droplets exhibit isotropy, forming a regular circular spreading area. By analyzing the wetting properties of molten AgCuTi on single crystal and polycrystalline substrates, it was found that the presence of grain boundaries significantly promotes wetting properties.