This study proposes and applies the Prophet model to forecast global population trends. By collecting, cleaning, and analyzing global and national population data from 1950 to 2021, we constructed a Prophet time series forecasting model to predict population changes for the coming decades. The results indicate that the global population will continue to grow, but the rate of growth will gradually slow down in the future, with the primary growth areas concentrated in Asia and Africa. Compared to traditional statistical models and machine learning models, the Prophet model excels in handling long-term time series data, automatically detecting trends, seasonality, and holiday effects, thus providing highly accurate predictions. However, population growth rates and numbers are influenced by various factors, so it is essential to consider these multiple factors comprehensively when analyzing population changes to fully understand the trends and reasons behind them. Despite not accounting for all possible influencing factors, the Prophet model demonstrates good applicability in real-world population forecasting.