The transient response analysis of the SLED based on the equivalent circuit is described. Then, a C-band SLED using TE0,1,15 mode cylindrical cavity with TE10-TE01 mode converter has been designed. According to the main RF parameters of the accelerator, the coupling coefficient is optimized to obtain the maximum multiplication factor. The key components of the pulse compressor include a 3 dB directional coupler, a TE10-TE01 mode converter, and a cylindrical cavity, which are simulated and optimized using 3D electromagnetic field simulation software. In addition, the function defining the relation between the coupling factor and aperture size is derived by a mathematical fitting method.