Against the background of the slowdown of investment growth in the manufacturing industry，China International Import Expo（CIIE）has played a positive spillover effect through five major paths，including market competition，supply chain structure upgrading，technology improvement investment，investment promoting by the super large market，and improvement of business environment. Through smoothing the function path of “expanding import and foreign investment→unblocking dual circulation economy→improving domestic supply-demand relations→ stimulating manufacturing investment→deepening international industrial division→expanding import and foreign investment”，CIIE can effectively promote the upgrading of manufacturing investment. Practice has proven that the past five successful sessions of the CIIE have played a significant role in expanding the scale of manufacturing investment，optimizing the structure of foreign investment in manufacturing，and leading new manufacturing investment trends. It is recommended to make further efforts in optimizing the exhibition settings of the CIIE，enriching investment and exchange activities during the exhibition period，and improving the quality of foreign manufacturing investment，in order to play a better role of the CIIE in upgrading manufacturing investment.