In order to investigate the effects of microstructure Oil film on the welding spatter in Zn electroplated steel, Zn electroplated surface and layer structure with USS-Paddition was observed using XRD, XPS and optical microscopy. Wettability of water drop on the Zn electroplated steel surface was measured using Z.Mei model. Oil absorption test was carried out using Oil pen. Morphology of spot welding and spatter with USS-P addition, applied current, and oil-spray or oil-without was observed using SEM and optical microscopy. Surface morphology of Zn electroplated steel showed finer structure as USS-P content increased. Wettabiliy on the Zn electroplated surface decreased with increasing USS-P content. Size of welding trace increased and spatter occured arround the welding part as applied current increased, whereas spatter disappeared as USS-P content increased and disappeared in case of oil spraying on the Zn electroplated surface.