Abstract: The sponge city special planning, a major basis for the planning and design of sponge cities, plays a leading role in the overall planning and construction process. By analyzing the limitations in the sponge city special planning under the framework of the “four waters”, this research puts forward suggestions for the optimization of the planning for semi-arid valley cities in Northwest China from the three aspects of problem identification, target determination and planning measures. It incorporates the “mountain-water-city” system analysis method, adds and refines the target indicators such as the proportion of soil erosion control, integrates and optimizes the corresponding planning measures, proposes a set of ideas for the preparation of sponge city special planning with the core framework of “mountain and water management, and city nourishment”, and launches discussions with the practice of sponge city special planning of Xining City.