A flat field hologrpahic concave grating is one whose spectral field is in a plane.If a multichannel photodetector receives spectrum signals on the plane

spectrum analysis can be more simply and quickly

and instantaneous spectrum analysis can be achieved.Not only loss of light energy will be less

but the spectrometer will also be miniature

with collimating and dispersing and converging by the grating.In this paper

we design the grating by the theory of holographic concave grating

and present the method which calculates the radius of the grating surface and the record parameters in the condition of the given mount parameters.Through rays tracing

we evaluate the designed grating by the spot diagrams of spectral images formed by the grating

and by the relevant line profiles.The results are satisfactory.