Abstract: The thermodynamics,kinetics,and flux balance of water electrolysis by solid oxide electrolysis cell（SOEC）were analyzed,and a thermodynamic equilibrium model was established using Aspen Plus. The predicted results were first compared with experimental data published in literature,and a good consistency was found. The effect of operating temperature,pressure,steam mole fraction of the cathode inlet gas,and air flow rate in the anode channel on the SOEC performance were then investigated. Finally,the influence of thermal energy reutilization on system efficiency was emphasized. The results indicated that the amount of thermal energy available for reutilization accounts for 26.53%-46.63% of the total input energy when the current intensity is 1.0 A/cm~2. If the SOEC system were properly configured,the waste heat utilization rate would be ＞ 52.27% when the current intensity is 1.0 A/cm~2. Compared with the case without heat reutilization,the system efficiency increases by 14.43%-26.54%. When operating at 0.1 MPa,1223.15 K,50% H₂O in the cathode channel and 10 mol/h air in the anode channel,the system efficiency reaches a maximum of 90.56% at a current intensity of 0.78 A/cm~2,25.89% higher than that without heat reutilization.