Abstract: Based on the theory of the ellipsoidal grating, the idea of cylindrical concave grating is put forward in this paper, the diffracting properties and collecting light ability of cylindrical concave grating are studied. The results show that the diffracting properties of cylindrical concave grating and spherical concave grating are similar under the condition of grazing incidence, but the cylindrical concave grating may be divided into certain congruent sectors along the direction of the grating generator for independent operation. Therefore, the grazing incidence cylindrical grating monochromator for mounting horizontal baffle plates may be used for the space-time resolving measurement of vacuum ultraviolet (VUV) spectrum of Tokamak plasma.