The comprehensive promotion of the level of manufacturing development and the creation of acluster of domestic advanced manufacturing industries is an important part of the Yangtze River Delta regionalintegration strategy, and the International Import Expo is an important platform for advancing this strategy.In order to explore the continuing impact of the such major conferences on micro manufacturing companies'value in the region, based on platform economics, the paper uses the data of 2,087 domestic manufacturinglisted companies from the fourth quarter of 2017 to the third quarter of 2019 to conduct empirical study byPSM + DID method. The results show that: First, the holding of the International Import Expo will significantlypromote the corporate value of manufacturing listed companies in the Jiangsu, Zhejiang and Shanghai regions;Second, this promotion will be more prominent in non-state-owned enterprises, and has a degree of continuity,in which instant quarter and the third quarter were the most significant; Finally, the return on investment andcash flow of listed companies' individual stocks were the main intermediaries for the promotion of short-termand long-term transmission, respectively.