The changes of current,voltage and light intensity of semiconductor bridge (SCB) with discharge time under capacitor energy supply excitation were conducted. The electroexplosion energy conversion processes and phase changes for SCB were analyzed based from the electric energy input and enthalpy change theoretical calculation. Results show that melting ratio,vaporizing ratio and ionizingratio of SCB are 61.1％,14.5％ and 70.3％ at 2.18 μs,3.48 μs,and 17.60 μs respectively when the capacitance is 22 μF and the charging voltage is 45 V.