The forward error correction codes with high coding gain are used in p assive optical access network to reduce requirement for transmission power and improve network performance. Low-density parity-check (LDPC) and orthogonal frequency division multiplexing (OFDM) modulation are introduced,and the passive optical network based on LDPC -OFDM coded modulation is built.10Gbit/s coded modulation signal and 2Gbit/s on-off keyin g (OOK) coded signal are transmitted as downstream and upstream in the 20km standard single mode fiber. The performance improvement of coded modulation over uncoded modulation is 3.9dB in downlink at bit error rate (BER) of 10－3. The performance comparison is also made between LDPC code and RS code in uplink, and the improvements of the LDPC code relative to RS(255,3) and RS(255,9) are 1.8dB and 2.3dB at BER of 10－3,respectively.