In order to develop a lower melting temperature filler alloy for brazing of aluminum alloy with high strength and low melting temperature, the eutectic compositions and temperatures of Al-Si-Zn system were determined by the thermal analysis. A typical eutectic composition was Al-4.2mass%Si-40mass%Zn, and the eutectic temperature was 808K. Spreadability of this eutectic alloy on 3003 alloy sheet coated with chloride flux was sufficient at 838K. Brazeability test was carried out with T-joint specimen in which brazing sheet was prepared by hot dipping. In the brazing of 3003/3003 and 3003/Al-5.5mass%Mg alloy pairs, flow of the filler metal was good and the fillet was satisfactory. On the other hand, in the case of Al-5.5mass%Mg/Al-5.5mass%Mg, no fillet formation occurred.