To reduce the overhead of the analysis of phase noise compensation (APNC ) method in coherent optical orthogonal frequency division multiplexing (CO-OFDM) system,we present a new re ducing overhead analysis of phase noise compensation (ROPC) me thod based on APNC algorithm.This method use impulse response processed with window (IRW) algorithm relied on LS estimation to filter the nois e outside the window,which improve can the accuracy of channel estimation.And th en the method uses the quasi-pilot-aided phase noise estimation which decrease s the number of pilots for phase noise compensation with the low complexi ty.The simulation results show that with the same BER,the number of pilots re quired for ROPC method is reduced by a factor of 2in comparison with that for the APNC method,which reduces the overhead of the s ystem.The ROPC algorithm′s BER is similar with that of APNC method with the laser′s linewidth of 0.7MHz and 4pilots,which improves t he reliability of the system.