Recent years have seen a mass manufacturing and production of portable electronic devices and gadgets, such as smart phones, digital notebooks, digital cameras, portable players like DVD player, PDA and MP3 player, Global Positioning System devices and health care devices, etc., Presently these all products have become the need of the peoples and mostly all of these products require a battery power supply. But the main problem is the limited capacity of battery, the amount of usage time provided from batteries is often far from ideal. Many of the electronics products users face this problem that the battery of their device runs out of energy at critical moments when they are required for important applications and it is not possible to have a power supply for every portable device; however, a common backup supply can resolve this problem. Normally the power bank does the following three functions; it charges the internal battery and provides power for external electronics devices. Thus in this project “Design of Power Bank with Buck-Boost Converter” is going to be designed and studied. There are certain methods for design of Power Bank, thus considering all methods; Power Bank will consist of different features which will fulfill mostly all specifications required to charge different gadgets with batteries connected in a serial or parallel manner inside the power bank as per requirement. It will give different power level outputs with special protection features like NTC (Negative Temperature Coefficient), and short circuit protection, etc., with efficient battery saving mechanism.