It is of great theoretical value and practical significance to clarify the multiple concurrent causality of digital industry agglomeration and release its promoting effect on economic development. Taking 30 provinces in China as the research objects, this paper explores the formation mechanism of digital industry agglomeration from the perspective of configuration, and further investigates its impact on the high-quality development of regional economy. It is found that under the market economy in Socialism with Chinese characteristics, building a high-level digital industry cluster requires the concerted efforts of the government and the market, and the goal of digital industry cluster cannot be achieved without any link; Digital industry agglomeration has promoted the high-quality economic development, and this influence has positive spatial spillover; The expansion analysis shows that with the improvement of the quality of regional economic development, the promotion effect of digital industry agglomeration on the high-quality development of regional economy shows a gradually increasing trend; Digital industry agglomeration has a stronger effect on promoting the high-quality economic development in the eastern and central regions than in the western region; At the same time, the impact of digital industry agglomeration on high-quality economic development has a significant threshold effect. The higher the level of digital industry agglomeration, the stronger its promotion effect on high-quality regional economic development. The research results provide theoretical and empirical support for promoting the construction of high-level digital industry cluster, further releasing the dividend of digital industry cluster and promoting the high-quality development of regional economy.