A Semiconductor Bridge (SCB) explosiveinitiator has many advantages such as shorter action time, better ignition consistency and higher reliability.The development of a SCB has traditionally been guided by an experimental approach.Experiments conducted worldwide show that the melting and vaporization of a SCB when heated by an electrical current is a very complex physical process.In this process, the bridge goes through multi-phase changes, i.e.in order solid, liquid, gaseous and plasma-state.This paper discusses the numerical simulation of the SCB working process when driven with a short low-energy pulse.In an effort to elucidate the behaviors of the SCB working process, the temperature distribution before the SCB melting and SCB discharge are presented.The basic semiconductor equations and heat transfer equation are described to evaluate the temperature distribution in the SCB.The results are obtained from finite-difference implementations.The edge gasification effect of SCB is proved by the curve of temperature distribution, and the double temperature characteristic of SCB is shown.Finally, a SCB discharge model is established.The result shows that the bigger the external voltage, the longer is the discharge time.