Abstract: Macro-band method is a method of characteristic line based on non-uniform ray tracing. When the geometry of the system is complex, the density of the characteristic line generated by this method is huge and the amount of calculation increases sharply. In order to overcome this problem, the cell modular non-uniform ray tracing method was adopted to reduce the total length of the macro-band and the characteristic line. In addition, the boundary discretization method was introduced for the dislocation of the characteristic line at the cell coupling boundary. Numerical results show that the method of characteristic line based on cell modular non-uniform ray tracing has high computational efficiency and accuracy and can meet the needs of common neutron transport calculation in PWR.