In this paper the lifetime of the terminal energy level has been considered in the rate equations of the fast Q-Switched four-level laser. Computer solutions are pre-sented. The effects of the terminal energy level lifetime, the initial inversion popula-tion density, the stimulated emission cross-section and the cavity length on the behavior of giant laser pulses and multipulses have been studied in detail. The optimization and miniaturization of electro-optically Q-Switched lasers are discussed.