A double-pass grating imaging spectrometer is proposed and demonstrated. The traditional entrance slit is replaced by a middle reflective slit, which is used as a spectral filter rather than a spatial filter. The light from the scene passes through the same dispersive grating twice. The full image of the scene can be obtained with a snapshot. Therefore, the stripe noise and image distortion caused by image mosaicking can be eliminated. Besides, the target is easier to be captured and focused, just like using a camera. This method can be used to obtain clearer spectral images of the scene conveniently and quickly.