A novel all-optical half-subtracter combination logic scheme is demonstrated, based on two semiconductor optical amplifiers (SOA) and three narrow optical bandpass filters (NOBPF). By utilizing four-wave mixing (FWM), cross-gain modulation (XGM) in the SOA and through adjusting narrow optical bandpass filter central wavelength, the first SOA generates ·B logic and provides borrow bit of half-subtracter, simultaneously the SOA generates XNOR logic; the second SOA generates NOT logic, two cascaded SOAs engender XOR logic and provides difference bit of half-subtracter. In the experiment, all-optical half-subtraction Boolean calculation is achieved between 10 Gb/s PRBS signals.