Phase change heat transfer of a gold particle irradiated by ulter-fast laser was studied. Position of solid-liquid interface was determined with coupling interface energy balance equation and interface tracking method for nucleation dynamics. In addition, effects of laser parameters on sintering process were studied. It showed that as laser irradiates gold particle vertically, melting phenomenon occurs mainly in poles of particle. Bottom of particle melts earlier than top and melting volume is smaller. As laser pulse width becomes shorter melting is earlier and melting volume increases. Melting degree of particle increases with laser heat source fluence.