A compact, low cost, high speed, non-destructive testing NIR (near infrared) spectrometer optical system is developed based on digital micro-mirror device (DMD). The application of DMD as wavelength scanning element in a traditional lens optical system enables the design of compact grating spectrometers capable of acquiring full spectra using a single detector element. Firstly, comparing with the traditional optical system, there is a new structure with a single detector. With the characteristics of DMD, the structure of the spectrometer system is proposed. After calculating the parameters of the optical path, ZEMAX optical software is used to simulate the system. Finally, the prototype is fabricated and calibrated. Designed for a wavelength range between 900 nm~1 500 nm, the spectrometer optical system features a spectral resolution of 19nm with the area of 70 mm×130 mm. If the width of slit is more than 200 μm, decreasing its width can increase the resolution of this prototype and the change of intensity is slow. Adding an aperture in the prototype can reduce the curved of the slit image in the spectrum. The system satisfies the demand of Near Infrared(NIR) micro spectrometer with a single detector.