Optical orthogonal frequency division multiplexing (O-OFDM) systems present high peak-to-average power ratio (PAPR), conventional selective mapping(C-SLM) scheme has high computational complexity, and some low complexity SLM scheme show poor suppression performance on PAPR. In order to reduce the computational complexity, meanwhile taking into account of the inhibition performance of PAPR, proposed is a joint-improved PAPR reduction scheme which combines a low-complexity SLM scheme with the Clipping technology. In the low complexity scheme, the real and imaginary parts of the O-OFDM signal are processed separately to obtain more candidate signals, and then combining with the technology of Clipping, signals are defined in the threshold value range, thus the signal with minimum PAPR is selected to obtain the best PAPR suppression performance. Simulation results show that the proposed scheme has better performance and higher utilization value.