According to the defect of the high pe ak-to-average-power-ratio (PAPR) in optical orthogonal frequency division mu ltiplexing (O-OFDM) systems,the selected mapping (SLM) method for PAPR reduction technologies has been deeply studied.An improved PAPR reduction t echnology,which combines the idea of the second PAPR selection and the low-complexity SLM scheme,is proposed .The improved SLM scheme,compared with the conv entional SLM scheme, can significantly reduce the computational complexity.The simulation analysis s hows that the improved SLM scheme can reduce the computational complexity more than 50% for the optical OFDM systems with 256subcarriers.And with the increase of the number of subcarriers,the computational complexity can be effectively reduced.At the same time,the PAPR reduction performance of the improved SLM scheme is superior to that of the conventional SLM scheme.As a result,the improved SLM scheme can further pro mote the practical value of the low-complexity SLM scheme.