The invention discloses an energy-saving water supply system for an office factory building of an enterprise. The energy-saving water supply system includes a water storage tank and a main annular pipe arranged along a main annular road. A first water inlet pipe, a first valve, a second water inlet pipe and a second valve are arranged on the main annular pipe in sequence. The first water inlet pipe and the second water inlet pipe are communicated with a municipal water supply system. The first valve, a first check valve and a flowmeter are sequentially arranged on the first water inlet pipe and the second water inlet pipe in the water inlet direction. A fire hydrant is disposed at the corresponding position of the main annular pipe. A third water inlet pipe and a fourth water inlet pipe are arranged between the water storage tank and the main annular pipe. The third water inlet pipe and the fourth water inlet pipe are located on the two sides of the first valve or the second valve respectively. The second valve and a second check valve are sequentially disposed on the third water inlet pipe and the fourth water inlet pipe in the water inlet direction. The overhauling of different sections of the main annular pipe is achieved, and a function of feeding water to the water storage tank 12 by the municipal water supply system is not affected in the overhauling process.