Abstract: The wettability of nickel based amorphous filler metal foil BNi-2,BNi-3 and iron based amorphous filler metal foil Fe₇₈B₁₃Si₉ on plain carbon steel pipe were investigated under the same welding condition:bonding temperature of 1200℃,holding time of 50 seconds and flowing argon atmosphere.Results show that BNi-2 foil has excellent wettability,namely the wetting angle is about 10 degree,and its flowing is not sensitive to the surface oxide film on base metal;the wetting angle of BNi-3 foil were about 45 degree;the wettability of iron based amorphous filler metal foil Fe₇₈B₁₃Si₉ is very poor.The excellent wettability of BNi-2 foil was attributed to the excellent metallurgical consistence(high solid solubility of Cr in iron and reaction between Cr and C in steel)and lower melting point of BNi-2 amorphous foil.