This thesis examines the impact of extended life expectancy on economic growth and explores whether it is a "dividend" or a "burden". Through theoretical analysis and cross-national empirical data, the research verified that there exists a nonlinear relationship similar to the Preston curve between the two, that is, a logarithmic influence that first promotes and then inhibits. The thesis finds that there are significant differences in the influencing mechanisms between developed countries and developing countries. In developing countries, the extension of life expectancy mainly promotes growth through the accumulation of human capital. In developed countries, however, its positive effects are often offset by the financial pressure brought about by population aging. The thesis adopted a variety of measurement methods such as correlation analysis, regression model and Chow test. Based on the research findings, the paper puts forward differentiated policy recommendations for two types of countries. For instance, developing countries should strengthen their health and education foundations, while developed countries need to reform their pension systems to address the challenges of an aging population.