Abstract: Resonance self-shielding calculation is very important in the reactor physics calculation. This paper shows a resonance module for the lattice physics code LATC developed based on the PWR fuel assembly features. The resonance self-shielding model adopts the well-proven equivalent theory, and the first collision probability uses two-term rational approximation. The module can read the WIMSD and improved WIMSD format multi-group cross section data libraries, and can provide the macro cross section for LATC transport calculation. It involves a large amount of calculation and data transfer, so the data structure has been optimized in this module to accelerate the processing. Based on the LATC code, the resonance module was preliminary verified. Comparing with DRAGON program, the results show good accuracy and adaptability for the PWR.