The design method, simulation and test results of a small rapid scanning type near-infrared spectrometer (NIR) based on improved Czerny-Turner optical structure were presented. To reduce the stray light caused by multiple diffractions and multiple reflections, the optical structure was arranged and optimized by the Cary principle. The simulation and analysis result using optical software TracePro were also presented. Stray light was suppressed in the improved structure effectively. On the order hand, in order to increase the scanning speed, a harmonic motor was used to drive the grating directly instead of the traditional structure with a screw driver between the motor and the grating. Finally some basic test results of the near infrared spectrometer were presented, and glucose solution was analyzed by qualitative experiments.