Photoconductive switch can be used in high power microwave system. The breakdown resistance field strength of SiC photoconductive switches is mainly limited by packaging. The packaging method cannot effectively solve the problem of electric field accumulation when the copper electrode leaves the SiC substrate, which leads to the application field strength of SiC far lower than the breakdown resistance strength of SiC crystal. The effects of the structure of the electrode and the connection structure of SiC to the electrode on the interfacial field intensity are studied. The electric field enhancement at the interface is reduced by optimizing the edge of the electrode and the SiC crystal structure. The breakdown voltage of optimized electrode structure is tested. The results show that the electric field enhancement can be effectively reduced by optimizing the electrode chamfering and burying under the interface between SiC crystal and electrode. Under the structure of circular chamfering and interface connecting with solder, the SiC photoconductive switch breaks down at the voltage of 22 kV.