Abstract: The flow and heat transfer characteristics of AFA fuel assembly for VVER reactors have been investigated using computational fluid dynamics (CFD) simulation. The flow field, pressure drop and temperature distribution of the coolant in AFA under normal regime have been calculated. The results show that the pressure drop of the spacer grid of AFA is lower than that of the grid having mixing vane. The stagnation zone of coolant appears around the rim of the spacer grid and causes higher temperature in the periphery region of AFA. The power ratio of the circumferential pin around instrumental tube (K_c) with different values has a great effect on the measured temperature of the coolant at FA outlet. The results can be referred in the setting of temperature warning value (ΔT_t) for the reactor core during the operation of nuclear power plants.