All-optical RZ to NRZ format conversion based on cross-phase modulation in the high-nonlinearity fiber is numerically simulated. Performances of converted NRZ signals from RZ data streams with different duty cycles are analyzed and compared. Results indicate that the duty cycle of RZ data does affect the converted NRZ signal, with a rational value between 30% and 50%. Meanwhile, RZ to NRZ format conversion is experimentally demonstrated at 10 Gb/s data rate with 33% duty cycle. Signal spectrum before and after HNLF, typical eye diagrams and bit-error-rate (BER) are measured. Less than power penalty 1 dB is obtained in bit error rate 10-9 after the format conversion. Further experimental results confirm the feasibility in 160 Gb/s high-speed systems.