Based on a bench-scale membrane wall entrained-flow gasifier, a flow and heat transfer model of working fluid was established for the study of hydraulic characteristics of the membrane wall. The effects of structure parameter and operating parameter on the working fluid maldistribution were also analyzed. The simulation results show that velocity of working fluid decreases while static pressure increases along flow direction in the distribution header. In the collection header, the velocity of working fluid gradually increases along flow direction, while the static pressure decreases in the same direction. Higher inlet-outlet pressure drop and flow rate are observed in the cooling tube which is farther from the header inlet. The maldistribution of working fluid can be reduced by diminishing the cooling tube diameter and enlarging the angle between the tubes. The maldistribution increases with the increasing inlet velocity of working fluid. Changing the inlet temperature of working fluid has negligible effect on its maldistribution.