The utility model relates to a portable large-capacity battery pack. The portable large-capacity battery pack is designed for a handheld electric tool, an electric pump and the like in the electric power industry, and is especially suitable for being used in large-workload sites. The portable large-capacity battery pack comprises a portable battery pack box body and a cell module. The cell module is arranged in the battery pack box body. A plurality of lithium battery units are connected in series so as to form the cell module. The cell module is provided with a protection circuit. The portable large-capacity battery pack is characterized in that the portable large-capacity battery pack further comprises an electric quantity display device, an electric quantity display switch, a cell charging socket, an output socket, an output plug, a connecting wire, an air balance valve and a battery shell. The battery capacity of the portable large-capacity battery pack is large. The portable large-capacity battery pack is suitable for high-altitude and large-workload applications. The portable large-capacity battery pack has security protection functions such as short-circuit protection and over-discharge protection, so that personal and property safety can be protected. The portable large-capacity battery pack has an electric quantity display function, so that embarrassment of insufficiency in electricity in a site can be avoided easily. With the portable large-capacity battery pack adopted, a variety of kinds of voltages and capacities are available.