In order to improve the theory of positive externalities in the process of industrial agglomeration, from the perspective of cost sharing and benefit sharing, the research methods for institutional engineering were used to study the positive externalities in the process of industrial agglomeration. Taking the media industry agglomeration as an example, three institutional models of cost-sharing, revenue-sharing and hybrid media industry agglomeration were constructed. The research shows that the agglomeration effect of the cost-sharing media industry is the best, followed by the agglomeration effect of the hybrid media industry, and the agglomeration effect of the revenue-sharing media industry is poor. Subsidies can improve the agglomeration effect of the hybrid media industry and revenue-sharing media industry. The research conclusions can provide a theoretical reference for the government to develop local industries.