The AgCuZnSn brazing filler metal was prepared on the Ag45CuZn brazing filler metal by brush electro-plating tin. The effect of current density, relative velocity of cathode and anode, bath electrolyte temperature, voltage and time on current efficiency and tin content of AgCuZnSn brazing filler metal were investigated. The surface morphology of tin coating and the brazing filler metal wettability were observed using scanning electron microscopy (SEM) and wetting test furnace. The results indicate that current efficiency and tin content initially increase and then decrease with the increase of the current density, brush electro-plating voltage and temperature. As the increase of the relative velocity of anode and cathode, the current efficiency gradually reduces, and the tin content initially increases and then decreases. With the increase of the brush electro-plating time, the current efficiency has no significant change, but the content of tin increases. SEM images show that a smooth and uniform surface morphology of the tin coating with tin grain size of about 0.3~1.8 μm and porosity of 0.82% is obtained. The non-directional tin granular parallel to the surface direction of Ag45CuZn brazing filler metal growth is better than that of perpendicular to the surface of the growth. Compared to Ag45CuZn brazing filler metal matrix, when 2.38 wt.% metal tin is brush electro-plated on Ag45CuZn brazing filler metal, the wetting area of Ag45CuZn brazing filler metal increases by about 19.5 %, and the Ag43.92Cu28.65Zn25.05Sn2.38 brazing filler metal possesses a good wettability