Abstract: Molten salt reactor (MSR) adopts molten fluoride salt mixture as fuel and coolant, and the features of neutronics and thermal-hydraulics of MSR are different from those of traditional solid-fuel reactors due to flowing fuel. Steady state analysis of a preliminary design of thorium molten salt reactor (TMSR) was performed based on MSR analysis code MOREL2.0. The results show that fuel flow brings a significant influence on the distribution of delayed neutron precursors and leads to 169 pcm of reactivity loss, k_eff decreases as the increase of time spent through external loop and tends to be stable after 80 s, and TMSR has a negative inlet fuel temperature coefficient and inherent safety characteristic.