In order to meet the urgent requirements of detecting atmospheric trace gas in space, a limb sounder prototype of atmospheric trace gas for spaceborne remote sensing is designed and developed. The optical system of the prototype is composed of an off-axis parabolic telescope and a modified Czerny-Turner spectrometer, and the working wavelength band from 380 nm to 570 nm. The root-mean-square spot radius is less than 9 μm over. The astigmatism is corrected, and the good image quality is obtained over the working wavelength band. The mass of the prototype is 12 kg, the volume is 420×350×200 mm3, the spatial pixel resolution is 0.5 km, and the spectral resolution is 1nm, and all the requirements are satisfied. The field sounding experiment is implemented using the limb sounding prototype. The spectral data measured is compared with spectral data simulated, and consistent with spectral data, which indicates that the limb sounder prototype has good function and performance, and satisfies the application requirements of sounding of atmospheric trace gas.