In order to meet the needs of high-precision measurements of atmospheric trace constituents, accurate description the slitfunction of the detector for atmosperic element measurements is required. Considering the characteristic of large field, wide wavelength range, high spatial and spectral resolution, a slitfunction measurement stimulus has been developed. Firstly the theory of slitfunction measurement was supplied. The slitfunction measurement can output high-resolution and wide spectrum and the slit function of the detector for atmosperic element measurements was tested by building an experimental device, The mathematical expression was offered accurately, and the results were analyzed. The results show that: the spectral resolution is about 0.423~0.597 nm of the detector for hyperspectral atmospheric element measurements, and the slitfunction approximating Gaussian distribution. Since the large field of the detector for hyperspectral imaging instrument, a phenomenon of smiling was appealed. This result led to the spectral resolution in the edge of the field slightly below that in the center of the field. For accurate and complete measurement of the slitfunction an echelle monochromator has been developed, which offers a number of high-resolution spectral lines, that can be used to spectral calibration.