This paper presents a new topology of uninterruptible power supply (UPS) by using an extended boost Z-source inverter.In this project a new topology of uninterruptible power supply (UPS) implemented using extended boost source inverter. The Z-source concept can be applied to all dc-to-ac, ac-to-dc, ac-to-ac, and dc-to-dc power conversion. The extended boost Z-source inverter overcomes the conceptual and theoretical barriers and limitations of the traditional voltage source; current source and normal Z-source inverter. With this new topology, the proposed UPS can maintain the desired ac output voltage with reduced voltage drop and minimized voltage stress. The overall cost of the system has been reduced by reducing the battery utility. So, this system is more economical for UPS application. The proposed system is simulated using MATLAB / SIMULINK with the simple boost control scheme and various factors such as output voltage, boost factor and THD are analyzed.