The development trend of single-order diffraction grating is introduced. The feasibility of single-order diffraction grating is theoretically demonstrated, and a novel diffractive optical element named quasi-sinusoidal reflection type single-order diffraction grating(QSRG) is proposed. It can suppress higher order diffraction, and improve the signal-noise-ratio (SNR) and accuracy. The experimental results verify this new type of dispersion component, where the higher order diffraction components are efficiently suppressed, which accords well with theoretical prediction. These results are expected to be widely used in the reflection spectrum measurement system.