A novel high-entropy alloys (HEAs)-joining strategy was proposed by brazing Al0·3CoCrFeNi substrates at 1573 K in vacuum using a pure niobium interlayer. The brazed Al0·3CoCrFeNi joints have a eutectic structure of face-centered-cubic (FCC) and C14 Laves phases, exhibiting excellent strength-ductility synergy at both room and liquid-nitrogen temperatures.