Abstract: RIXS, Resonant Inelastic X-ray Scattering, is an x-ray spectroscopy technique used to investigate the electronic structure of molecules and materials. The requirement of it for source and spectrometer is extremely strict. Mastering its design idea, application method, performance, and so on is of great significance for future research. Through analyzing the design ideas of RIXS spectrometer, using LPF of theory analysis and calculating the varied-line-spacing grating parameters, this paper analyzes each aberration effect on the result of the energy resolution. The relationship between motor encoder and accurate angle of each part of spectrometer is needed during setting up and operating. Thus a non-contact measurement using visible laser was applied and it has been proved to be effective. Before the first commissioning of XFEL, the spectrometer was calibrated by X-ray in synchrotron end station for its energy resolution. The SHADOW program simulation shows that the performance of spectrometer meets the requirement of design and experiment.