Abstract: Efficient utilization of water resources is one of the key measures to alleviate the contradiction between supply and demand of water resources in the water-deficient areas. Therefore, how to evaluate the utilization efficiency of water resources in a country or a region is a basic scientific problem to be solved in water resources management. Existing water resources utilization efficiency evaluation indicators mainly include water consumption per ten-thousand-yuan GDP, agricultural irrigation water utilization coefficient and so on. However, these indicators represent the comprehensive water use level of a country or a region. They cannot reflect the imbalance of water use efficiency within the region, nor can they express the economic volume supported by different water use efficiency levels. Therefore, they cannot identify low-efficiency water users and it is difficult to make precise regulation for the low-efficiency water users. This paper presents a spectrum analysis method for water resources utilization efficiency. Based on the Gamma function, this study analyzes the different water use efficiency and its corresponding economic scale, and then calculates the proportion of the economic volume corresponding to different water use efficiency to the total economic volume (as the probability density) and draws the spectrum curves of water use efficiency. Using this method, the research on the spectrum of water resources utilization efficiency in China is carried out. Based on the water consumption per ten-thousand-yuan GDP in different provinces and corresponding GDP data from 1998 to 2016, the spectrum curves of water resources utilization efficiency are drawn, and the evolution trend of regional water resources utilization efficiency in China is revealed. The spectrum analysis method of water use efficiency reflects the imbalance of water use efficiency within the region by analyzing the distribution of water use efficiency and its corresponding probability density, which can provide a scientific basis for water resources management and precise regulation of efficient utilization.