The breakdown characteristics of 4H-SiC JBS diodes with a JTE termination was studied. First, the impacts of the ion implantation dose, lateral length and interface charge of the JTE terminal on the breakdown voltage were analyzed by simulation. The experimental samples were fabricated based on the optimized process parameters. The measurement results showed that the forward threshold voltage was 152 V, the specific on-resistance was 212 mΩ·cm2, and the breakdown voltage was 1 650 V. The forward current was mainly thermal emission mechanism, while the reverse current had strong voltage and temperature dependence. Finally, the high temperature reverse deviational stress aging test was carried out, and the results showed that the breakdown voltage showed a downtrend.