The key of water-saving and high-yield cultivation in wheat is to establish the population structure with high photosynthetic efficiency and low water consumption. For this reason, it is need to define the suitable control index of wheat population for water-saving and high-yield. In this paper, the ear-leaf ratio (the ratio of the number of ears to the total area of up 3 leaves in crop population, ears/m²) as a control index was studied including it's variation and it's relationships to photosynthetic performance of population and water use under the conditions of different varieties, irrigation treatments and planting densities. The results showed that, the ear-leaf ratios at the booting, anthesis and filling stage all increased as irrigation reduced or planting density increased. Under the condition of water-limited irrigation, there was significant difference in the ear-leaf ratio among varieties. On the basis of suitable leaf area, with the increase in the ear-leaf ratio, the non-leaf area index (NAI) of the population was increased, the illumination condition within the canopy was bettered obviously, the photosynthetic efficiency of the population was improved; the transfer percentage of reserves in non-leaf organs to grain was increased, the harvest index was increased; the yield was increased significantly and the water consumption was significantly decreased, which made the water use efficiency increase. Thus, it is put forward that the ear-leaf ratio of population is a suitable index to measure if the relationship between sink and source is compatible in the wheat water-saving cultivation system. The suitable ear-leaf ratio is 230-270 ears/m² in the water-saving, fertilizer-saving and high-yield wheat cultivation.