Abstract: Compton current is the main source that generates electromagnetic pulse. To improve the efficiency of calculation of Compton current induced by gamma rays in the atmosphere when the Monte Carlo method is adopted, based on the basic principle of Compton current induced by gamma rays，firstly, this paper calculates the attenuation of the Compton electron in the emitting direction, then a fitting function is figured out between the net electron current and the travel distance of the electron in a given range, finally the analytical and numerical method of calculation of the current density induced by mono-energy gamma rays in the atmosphere is given according to the formula of the differential Compton scattering cross section. The analytical and numerical results are compared with the results of the Monte Carlo calculation, the relative difference of the current densities is less than 10%, and the efficiency is increased by two orders of magnitude. The method provided in this paper can be applied in the fast computing of Compton current in the atmosphere.