Spectral imaging can simultaneously obtain two-dimensional spatial and one-dimensional spectral information of the object, which plays an important role in scientific detection and research. Conventional spectral imaging systems have problems such as complex optical systems, precision moving devices, and long exposure times, which greatly limit their application in many scenarios. In this work, a snapshot hyperspectral imaging system based on diffractive rotation is introduced, which can obtain the hyperspectral information of the target through single shot and image reconstruction. We also propose a series of system optimization methods to improve the performance and practicality of the system. The back focal length of the optical system is shortened by using the hybrid diffractive-refractive system, and the long-distance target can be detected by introducing a telephoto optical system in the front. Experimental results show that the optimization methods proposed in this work can effectively increase the exposure ability and improve the quality of the reconstructed image.