China is facing the dual impact of deepening aging and negative population growth under low fertility levels, and the economic development mode driven mainly by the expansion of labor and capital factors has shown a slight trend. To maintain high-quality economic development, innovation and technological progress have become the primary important driving factors, and technological diffusion is the fundamental way to achieve technological innovation and practical application. To this end, population size and quality are included in the analysis framework of technology diffusion, and it is found that technology diffusion is influenced by both population size and quality. Population size has a positive effect on technology diffusion, which has a pool effect, and the Matthew effect only appears under a certain population mass. Human capital has energy storage effect, which is mutually motivated by technology diffusion. From this, we can draw inspiration that, under the negative population growth and aging, as long as the population size is large enough, with the improvement of population quality, technology diffusion can be smoothly achieved and have a huge effect, thereby forming an innovative driving force to promote China's high-quality economic development.