A set-reset all-optical flip-flop(SR-AOFF) based on semiconductor optical amplifier Mach-Zehnder interferometer(SOA-MZI) is proposed. Simulation results show that low switching energy in the femto joule range, the transition time of less than 20 ps, high stability and high extinction ratio(ER) of 30 d B can be achieved, while AOFF output is power insensitive approximately. A set-reset all-optical flip-flop (SR-AOFF) based on semiconductor optical amplifier Mach-Zehnder interferometer (SOA-MZI) is proposed. Simulation results show that low switching energy in the femto joule range, the transition time less than 20 ps, ​​high stability and high extinction ratio (ER) of 30 d B can be achieved, while AOFF output is power insensitive approximately.