In order to reduce the influence of high Peak to Average Power Ratio ( PAPR) in DC-biased Optical OFDM (DCO-OFDM) system to the wireless optical communication.We propose a pilo t-assisted PAPR reduction technique.The scheme divides multiple discrete frequency-domain signal sequenc es into subblocks before IFFT conversion,then every subblock choose the best phase sequences in SLM scheme in dependently,those side information is encoded to error-correcting code and stored in a block-type pil ot,the maximum likelihood criterion is used to estimate the pilot signal at the receiver.It solves the problems of transportation and recovery of side information in the selected mapping scheme and improves bandwidth efficiency.An d the consequences is verified through simulation.a pilot-assisted M-QAM DCO-OFDM system is capable of redu cing the PAPR by over about 3dB than the original DCO-OFDM at a modest complementary cumulative distribution function (CCDF) point of 10－3 for M=16,its SNR is su perior 2dB to the original scheme at the bit error rate of 10－4.The theo retical expression of function and the simulation show that the pilot-assisted PAPR red uction technique results in high reduction in PAPR and reduces the influence of limiting noise on BER.The error- correcting code ensures the accuracy of the side information,promoting the system performance.