Abstract: Using the method of grey correlation analysis, the paper does an empirical analysis to the influence degree of the high-tech industry to economic growth of Yangtze river delta ,Pearl River Delta and Bohai Ring Megalopolis. Furthermore, the paper analyzes the contribution of the high-tech industry as a whole and various sectors of the high-tech industry to economic growth in the three urban agglomerations. It is found that high-tech industry plays an important role in promoting the economic development of the three urban agglomerations, and the relationship between high-tech industry and economic development is getting closer and closer. It is a significant strategy to vigorously develop the high-tech industry,which is a breakthrough to develop the economy of the three urban agglomerations.