美国作为全球科技和军事强国，其科技研发资助策略和方向对全球科技格局具有深远影响。文章基于BERTopic主题模型对2015年-2024年美国国防部关键科技资助项目进行主题挖掘和演化趋势分析，从主题分布及动态演化趋势角度对美国关键科技资助的战略布局及其构成因素进行了实证分析和系统梳理。美国国防部关键科技资助项目涵盖83个主题，大多数主题在时间维度上的频率变化相对平稳，仅少数主题呈现出显著波动或快速增长态势，体现了美国“集中资源突破核心领域，广泛布局孕育未来方向”的关键技术资助战略。总体来看，美国国防部在推进科技创新的过程中实现了基础研究与应用研究的协同并进，构建起以国家安全为导向的前沿技术生态体系。

As a global leader in science, technology and military power, the United States has a profound influence on the global scientific landscape through its research funding strategies and priorities. This paper conducts topic mining and evolution analysis of the key science and technology funding projects of U.S. Department of Defense from 2015 to 2024 based on the BERTopic model. From the perspectives of topic distribution and dynamic topic evolution, it provides an empirical and systematic examination of the strategic layout and constituent factors of U.S. defense science and technology funding. The results show that the Department of Defense’s key science and technology funding projects cover 83 topics. While most topics exhibit relatively stable frequency changes over time, a small number demonstrate significant fluctuations or rapid growth, reflecting a key technology funding strategy that emphasizes “concentrated resource investment in core areas while broadly fostering emerging directions.” Overall, the U.S. Department of Defense have achieved the advancement of basic and applied research in the process of promoting science and technology, thereby constructing a frontier technology ecosystem oriented toward national security.