Abstract: The three-dimensional power distribution of the molten salt reactor (MSR) designed by Oak Ridge National Laboratory (ORNL) was analyzed by using MCNP code. Besides, a multiple channel analysis code (MAC) was developed for the special geometry of graphite moderator design and coupled with MCNP code to analyze the neuron behavior as well as thermal-hydraulics of MSR experiment. The feasibility and accuracy of the analysis with coupled neutronics/thermal-hydraulics were validated by relevant results from the ORNL technical report. The results show that the coupling method can obtain accurately the power distribution, temperature distribution, pressure drop and mass flow distribution. This work is helpful for further design analysis and operation of MSR.