The enhanced conversion efficiency of the InGaP/GaAs dual-junction solar cell was demonstrated antireflection nanorod arrays. After self-assembled Ni clusters ,the nanorod arrays were fabricated by inductively-coupled-plasma reactive ion etching. The conversion efficiency were measured under one-sun air mass 1.5 global illuminations at room temperature. The short current of the nanorod arrays cell was enhanced 10.0% and the efficiency was enhanced 10.8%. We were also studied the light absorption efficiencies of the top InGaP and bottom GaAs cells under the influence of nanorod arrays. Surface nanorod arrays were not only as antireflection layers but also scattering sources. The nanorod arrays structure can be significant improved the maximum conversion efficiency.