In order to measure plasma X-ray produced by laser fusion in the 0.2~0.37 nm range, a focusing bent crystal spectrometer has been designed for measuring the spatial and temporal resolutions. The LiF crystal with a 2d spacing of 0.403 nm was elliptically bent at 700℃ for the dispersive element, the Bragg diffractive angles vary from 30 to 67.5 degrees, the bent LiF crystal was fixed on the elliptical stainless-steel substrate with an eccentricity of 0.9586 and a focal distance of 1350 mm. The X-ray spectrum emitted from the planar titanium target was photographed by using the bent crystal spectrometer coupled with the X-ray CCD camera at the XG-2 laser facility, the experimental result shows that the spectral resolution is up to 0.001 nm.