We propose a novel all-optical format conversion from the retu-to-zero (RZ) to the non-retu-to-zero (NRZ) based on single semiconductor optical amplifier (SOA) and optical band-pass filter (OBF). We demonstrate the proof of the principle experiment at 10Gbps by using the test SOA and OBF converter. The format conversion can be achieved with output extinction ratio of 11.51 dB. The BER is 5.5×10-9 when the power of NRZ is -10 dBm. The proposed scheme is robust and potential for applications in optical networks.