This paper calculated the industrial correlation and spreading effects from the perspective of industrial chain to analyze the optimization and upgrading of electro-mechanical industry based on the China input-output tables and extended tables from 2002 to 2015, as well as Japan input-output tables from 2000 to 2012. The result shows that the related industries of electro-mechanical industry in China are extensive, the intra-industry linkages are strengthened, and the demand-pulling role of the industry is stronger than the supply-driving role for the national economy. However, the R&D investment is insufficient, the technological progress is sluggish, the industry value-added rate is declining, the supply adaptability to demand changes is insufficient, and the output value structure and market adaptability need to be adjusted and optimized. Aiming at the problems, this paper proposed to take the coordinated development of industrial chain as the starting point, promote industry-university-research cooperation, increase research and development investment, adjust the technical structure of output, take the related industry demand as the direction, excavate the domestic demand, adjust the output market structure, improve the level of industrial servitization, extend the industrial chain, and coordinate the overall development of the industrial chain.