Abstract: The cross section is the important uncertainty source of the reactor physics calculation. It is of great significance to study the contribution of its uncertainty to the simulation results. Based on three nuclear evaluation data libraries, the 69 groups covariance library containing 70 kinds of main actinium nuclides and part of the fission products was generated using the NOJY code. The uncertainty analysis code SUACL was developed. The perturbed nuclear evaluation data libraries were generated using random sampling method based on the covariance library SUACL1.0/NCEPU developed by NJOY and 69 groups WIMSD library which can be downloaded from IAEA website. The PWR cell of NEA/OECD benchmark analysis was performed using perturbed nuclear evaluation data library and SUACL code. The result shows that the parameter pair of fission cross section, capture cross section and elastic scattering cross section for ²³⁵U and ²³⁸U contributed to the uncertainty of k_∞ agrees with that calculated by other well-known code, and the theoretical method is right and the SUACL code is developed correctly. The manufacturing parameters were also discussed based on random sampling method. The result indicates that the uncertainty of clad thickness has large effect on k_∞ because of its own large uncertainty.