Abstract: The lattice code in COSINE package is a two-dimensional and multi-group transport code which is mainly used for pressurized water reactor (PWR) assemblies or pin cells analysis. It is used to calculate few group constants and nuclei densities for the core code. As an improvement of the first phase code which using two-step homogenization method, the one-step homogenization technique based on MOC method is under developing to satisfy the design need in future. In the new technique, the fine structure of lattice was directly considered, so it could eliminate the error introduced by two-step homogenization method. In this paper, the cyclic characteristic method was employed to trace the neutron transfer which could make sure the characteristic passes through the geometry of the problem and assigns cell types to each individual cell. The cyclic tracking approach also could ensure perfect reflection in two dimensions problem. The MOC method could reduce the approximate and handle the complex geometry problem theoretically. However, the MOC method had disadvantage of low calculation efficiency for large storage in processing. The coarse mesh finite difference (CMFD) was used to accelerate the MOC method in this paper. In the development of LATC, the quality assurance (QA) process was implemented strictly to ensure the quality of code. The C5G7 benchmark was used as an example to verify the LATC code. The results show that the transport module in LATC is feasible.