Cu(InGa)Se2 (CIGS) solar cells become one of the most important thin film photovoltaic devices thus far. The doping of Sb has improved the grain size of CIGS thin film and therefore led to the enhancement of solar cell efficiency. Various approaches have been used for the Sb doping. Not many reports of electrodeposition of In, Ga and Sb alloy have been reported. In this work, the Sb thin film was coated over Cu film surface prior to the In and Ga deposition in order to form a Cu/Sb/In/Ga metal precursor. After selenization, the Sb doped CIGS film was prepared. The structure and morphology of Sb doped CIGS films were investigated compared with the undoped CIGS reference samples. A modified selenization method was proposed, which improved the grain size. Finally, the conversion efficiency of Sb doped CIGS based solar cells has been improved by 1.02%.