In the background of global warming, the carbon stock of afforestation is increasingly important. However, afforestation may consume large amounts of water, putting pressure on regional water resources. How to balance the carbon stock and water consumption of afforestation is a vital problem throughout the world. The Three-North Shelterbelt may be a vital carbon pool in the future while consuming a large amount of water. Therefore, it is urgent to predict and evaluate the future carbon stock potential and water consumption of the Three-North Shelterbelt. Indicator system assessment and MaxEnt are used to predict the potential forest habitat in the construction area of the Three-North Shelterbelt program. The results show that the area of the potential forest habitat is 0.58 million km² in the indicator system assessment. The potential forest habitat area totals 2.22 million km² in the MaxEnt results, including a poorly suitable habitat with an area of 1.35 million km². Scenario-Ⅰ is the hypothetical forest structure based on indicator system assessment, and scenarios-Ⅱ and scenarios-Ⅲ are based on the suitability level of MaxEnt model results. the potential carbon stock in scenario-Ⅰ is 0.71 billion Mg, and its potential water consumption in the forest growing season is 261.36 billion m³. The potential carbon stock in scenario-Ⅱ and scenario-Ⅲ is 3.54 billion Mg and 1.19 billion Mg, and the potential water consumption is 625.83 billion m³ and 631.28 billion m³, respectively. There is a strong correlation between carbon stock and water consumption, with a correlation coefficient of more than 0.718. Three-North Shelterbelt construction may bring huge carbon sink benefits, but it may also bring huge pressure to local water security.