The performance of a solid oxide electrolyzer cell (SOEC) is highly related to the stack structure and operating conditions. This work presents numerical investigations on a 10 cell SOEC stack under different operating mass flow rates. The distribution characteristics of the flow field, pressure field and temperature field with different mass flow rates are compared. The cell performances of SOEC at different layers in the stack are investigated and discussed. The simulation results show that the performances of SOECs in the stack are differentiated by mass flow rate and species mass fraction of fuel channels at different heights. Under the small mass flow rate condition, the Nernst voltages and operating voltages of cells at the lower positions are slightly higher than that of cells at upper positions. Under the large mass flow rate condition, the Nernst voltages and operating voltages of the cells in the middle stack is slightly higher than that of the upper and lower cells. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.