A full duplex radio over fiber (RoF) system,including the downlink with 64quadr ature amplitude modulation-orthogonal frequency division multiplexing (QAM-OFD M) modulated signals are analyzed and the uplink with 8plase shift keying orthogonal frequency division multiplexing (PSK -OFDM) modulated signals,of which downlink conveys a 60GHz millimeter-wave wi th different numbers of subcarriers (as the number is 64,8,256,2).The simula tion results show that the peak-to-average power ratio (PAPR) increases with asce nding subcarrier quantity.The bit error rate (BER) of the downlink signals with 256subcarriers is cl ose to 10－3.7 when the optical receiver power is － 18dBm,and in this case the receiving sensitivity is the best of all.For uplink ,the BER is lower than 10－3 when the receiver p ower is higher than －28.5d Bm.