Abstract: The radioactivity caused by neutron activation not only has a significant influence on the safety of reactor systems, but also produces a large number of nuclear waste post-processing problems after reactor decommissioning. In this paper an activation calculation code EuACT which was based on Euler exponent method and EAF database was developed. Activation characteristics of the cladding material including ZIRLO,Zr-4, M5 and N18 were calculated and analyzed. The results were compared with calculation results of the European activation code FISPACT. Irradiation time of 0.5, 1.0 and 1.5 a was selected in the calculation of the specific activity and the decay heat changing with the decay time for different cladding materials after reactor shutdown. Additionally, preliminary analysis of cladding material activation was also carried out. The results show that the calculation results of EuACT are in good agreement with those of FISPACT. From perspectives of specific radioactivity and decay heat, Zr-4 has more advantages than the other three materials.