Abstract: Nuclear fusion devices mostly run in pulsed condition, and different pulsed operation modes will influence the activation calculation. So, processing methods of pulse and selection of activation calculation methods determine the accuracy of the calculation results. In this paper, the method of transmutation trajectory analysis (TTA) and the analytic solution formula were used to calculate the change of the nuclide quantity with time in the reaction chain. Meanwhile, the back-tracking algorithm was used to search all the reaction chains involved in the calculation. To solve pulsed neutron activation problem, the steady state (SS) method, equivalent steady state (ESS) method and continuous pulse (CP) method were adopted to approximately handle real pulses, which simplifies the calculation process. On this basis, a pulsed neutron activation calculation program TACT was developed. Finally, based on the activation benchmark of natural Fe, test calculation was made according to the typical pulse history of inertial fusion energy (IFE) and magnetic fusion energy (MFE) experimental reactor systems, and the accuracies of different equivalent methods of pulses were compared. The results show that for IFE and MFE mode, using ESS method in the beginning of CP method has better results than other methods, for CP method, just keeping a proper number of pulses in the end can achieve a certain precision.