We propose an approach to generate optical triangular-shaped pulse train with tunable repetition rate using quadrupling radio frequency (RF) modulation and optical grating dispersion-induced power fading. In this work, a piece of chirped fiber Bragg grating (FBG) is employed as the dispersive media to remove the undesired 8th harmonic in optical intensity. Thus, the generated harmonics of optical intensity can be corresponding to the first two Fourier components of typical periodic triangular pulses. This work also analyzes the impacts of the extinction ratio and the bias voltage drift on the harmonic distortion suppression ratio. After that, the value of the extinction ratio and the range of the bias voltage drift can be obtained. The advantage of this proposal is that it can generate high order frequency-multiplexed optical pulses train which can be applied in all optical signal processing and other fields.