This study was aimed to obtain higher efficiency in gene transfection into K562 cells and to study the role of green fluorescence protein (GFP) as a reporter system. Transfection efficiencies with different methods including electroporation and lipofectamine 2000 transfection, were observed and calculated under fluorescent microscopy by using GFP as a reporter system. The results showed that the transfection efficiency with electroporation (10%) was higher than that with lipofectamine 2000 (1%). In conclusion, the electroporation is a more ideal method for introduction of foreign gene into K562 cells. GFP can be used as a reporter system for optimizing transfection of K562 cells.