An optical arbitrary waveform generator based on two fiber Bragg grating (FBG) arrays with independent phase control is proposed. It is composed of an amplitude controller and a phase controller. In the amplitude controller and phase controller, the controllable components are the FBG arrays. The FBG arrays comprise radial arrangement of several FBGs and fiber stretchers. The amplitude and phase of each spectral line of the output signal are controlled by only adjusting the fiber stretchers, which results in optical arbitrary waveform pulse. The amplitudes of spectral lines of the output signal are insusceptible to adjusting the fiber stretchers in the amplitude controller. Adjusting the fiber stretchers in the amplitude controller can affect the phases of spectral lines of the output signal. So the amplitude controller should precede the phase controller to be adjusted.