The current Russia-Ukraine war has pushed the issue of oil and gas security to a new strategic height. Correctly judging the future supply and demand of natural gas is of great strategic significance for the construction of major natural gas energy security projects. This paper innovatively divides natural gas consumption into three categories: survival, production, and non-bottom-line consumption, to predict medium- and long-term natural gas consumption under the condition of multi-factor collaborative uncertainty, to make a comprehensive study and judgment of the natural gas supply and demand situation under the bottom-line thinking. The results show that: first, under the three scenarios of recoverable reserves, natural gas production will peak in 2030, 2033, and 2037, and the peak production will be 2441.46, 346.492 and 422.795 billion cubic meters respectively; second, by 2030, the production The lowest consumption accounts for 31.70% of the bottom-line consumption, but its average annual growth rate far exceeds the survival consumption; third, the bottom-line consumption in 2025 and 2030 will reach 3057.19-3578.61 and 370.495-473.081 billion cubic meters respectively. If the cascade gas consumption thinking is strictly implemented, Subsistence consumption can basically achieve self-sufficiency under any production scenario, while the lowest self-sufficiency rate of production and consumption under the most optimistic scenario of natural gas production at the end of the "15th Five-Year Plan" does not exceed 52%, and even under the scenario of 1 times production and consumption may be completely dependent on external sources; Fourth, in the scenario of 2 times or 1.5 times the natural gas production, the external dependence of natural gas can be strictly controlled within 50%; the effect of using different scenarios to reduce the external dependence of natural gas is limited, and the maximum reduction of natural gas external dependence is 8.71%. The research conclusions are of great significance for ensuring the balance between the supply and demand of natural gas in my country and implementing the energy security strategy.