Background: With the development of the current nuclear reactor system

some characteristics such as complex structure

material variety and diverse spectrum of reactor cores need more and more computation consumption for reactor physics. Graphic Processing Unit (GPU) computing technology is widely used on the reactor calculation due to its rapid development. Purpose: This paper illustrates the GPU computing environment based on Compute Unified Device Architecture (CUDA) architecture

which is established on the design platform of Thorium Molten Salt Reactor (TMSR). And the neutron three-dimensional diffusion calculation module of the reactor would be transplanted into the GPU for testing and verification. Methods: First of all

center difference method was used to deduce the difference equations of three dimensional diffusion calculations

make it suitable for GPU. Then

the over relaxation iteration method was applied to solve these difference equations. Finally

the over relaxation iteration algorithm was studied in the parallel implementation of GPU processes. Results: The results show that the transplantation of GPU computing module section can be used to obtain correct output

and it can effectively improve the computing speed. Conclusion: The GPU computing environment on the TMSR design platform can work normally by carefully transplanting of several key methods for difference equations based on the CUDA of GPU. Abstract