Abstract: In view of the feature of the tightly coupling between neutronics and hydraulics in the molten salt fast reactor, the turbulent transport effect of delayed neutron precursor in molten salt advanced reactor transmuter (MOSART) was investigated using the developed three-dimensional multi-physical coupled code TMSR3D. The calculated results indicate that the influence of turbulent diffusion on the effective multiplication factor and neutron distribution is very small, and the influence on the distribution of delayed-neutron precursors is larger and depends on the distribution of the turbulent kinematic viscosity, the turbulent Schmidt number and the delayed neutron precursor group.