Abstract: Aiming at the triangle unstructured grid, based on the domain decomposition technique, a new direction parallel S_n sweeping algorithm was developed with the utilization of the independence of different neutron flight directions during the Sn sweeping process. It was verified with a mono-group S₈ neutron transport calculation problem. The results show that when the CPU number is 32, the speedup ratio is 23.57, and the parallel efficiency is 0.736.