Current mode fuzzy-tuning proportional-integral (PI) control of UPS (Uninterruptable Power Supply) inverter is presented in this paper. Double loop current mode and fuzzy logic controller are combined in this control scheme. Double loop current mode control scheme includes two control loops as voltage and current. Output voltage and filter inductor current are used as feedback variables in voltage control loop and current control loop respectively. In voltage control loop, voltage feedback gain is adjusted by fuzzy-logic controller (FLC). The input variables of the FLC are the output voltage error and its derivative and the output variable of the FLC is voltage feedback gain. This control scheme is simulated using C++ and PSIM and implemented using Texas Instruments TMS320LF2407 DSP (Digital Signal Processor). Simulations and implementation are realized under linear, nonlinear and fluorescent loads. The results prove that this control scheme provides low total harmonic distortion (THD) and fast dynamic response.