Abstract: Based on the ENDF/B-Ⅶ.0 nuclear evaluation data library, an improved multi-group cross section data library NECL2.0 was produced for Bamboo-Lattice code by using the nuclear data processing code NJOY and LATTICE_PRE. The results based on benchmark and numerical analysis show that the calculation results of infinite multiplication factor k_inf, fission rate distribution and fewgroup homogenized cross section by using NECL2.0 library agree well with the corresponding reference values. Considering the resonance of AgIn-Cd can increase accuracy of k_inf by 1 000 pcm. Compared with reference values, the maximum relative deviation of fission rate reduces from -0.97% to -0.53%. Considering the resonance of zirconium in cladding can improve the accuracy of k_inf by about 60 pcm.