Abstract: The transport calculation module of neutronics lattice code KYLIN-Ⅱ adopts the method of characteristics, which has higher calculation precision and can be applied to the complex fuel assemblies in the reactor. However, when the number of grids, energy groups and feature lines is large, the calculation time is longer and the calculation efficiency is lower. Therefore, parallel optimization is needed to improve the calculation accuracy. It is found that the calculation of characteristic line scanning and high-order scattering source updating is time-consuming through performance analysis. In this paper, parallel optimization was realized by parallel energy group based on MPI, E-exponential optimization, angular flux spherical-harmonic expansion and so on. The results show that the parallel optimization calculation precision is high, E-exponential is effective in calculation of characteristic line scanning, and angular flux spherical-harmonic function expansion is very effective in high-order scattering source updating. The optimized transport calculation module of KYLIN-Ⅱ has a significant acceleration effect and can meet project needs.