中国积极采取“引进来”和“走出去”战略应对产业链结构变化，通过吸引外资和对外投资破解“卡脖子”产业链瓶颈问题，进一步提升产业链关键环节自主可控程度。利用2000—2023年中经网统计数据库，结合投入产出表和投入产出延长表数据，聚焦双向FDI能否提升“卡脖子”产业链关键环节自主可控程度，研究发现：①双向FDI能有效提升“卡脖子”产业链关键环节自主可控程度，其对产业链中心度的提升作用强于产业链中介度；②双向FDI提升“卡脖子”产业链关键环节自主可控程度为百分位数的增函数，作用强度由大到小依次为双向技术溢出、OFDI逆向技术溢出和FDI技术溢出；③技术创新作为中介变量，在双向FDI与“卡脖子”产业链关键环节自主可控程度之间发挥单一中介作用；④双向FDI提升“卡脖子”产业链关键环节自主可控程度存在内部“双门槛”和外部“单门槛”效应；⑤双向FDI提升“卡脖子”产业链关键环节自主可控程度存在区域、产业和时段异质性。据此，提出加大双向直接投资扶持力度、加速推进人才强国战略、充分发挥新型举国体制优势、大力发展新质生产力、进一步破解“卡脖子”产业链技术瓶颈等政策建议。

Two-way direct investment of "bringing in"(inward investment) and "going global" (outward investment) is the carrier of the dual circulation of domestic and international markets, and the technology spillover effect of inward investment and the reverse technology spillover effect of outward investment have synergistically improved the internal structure and the traditional layout of China's industrial chain. Therefore, it helps to break through the technological bottlenecks of the key links of the industrial chain,further enhance the degree of independence and controllability of key links in the industrial chain. The Fourteenth Five-Year Plan and the 2035 Vision explicitly states the specific requirements of "guiding the key links of the industrial chain to remain in China,adhering to the equal importance of " bringing in " and "going global ",improving the industrial chain protection mechanism,and further upgrading the level of modernization of the industrial chain". Thus, the question arises of how to utilize two-way foreign direct investment (FDI) to increase the independence and controllability over key links that are bottlenecks in the industry chain becomes a core issue to promote the safety and stability of key links in the industrial chain.
From the perspective of two-way technology spillover,this paper focuses on the issue of two-way FDI to increase the independence and controllability over key links in the industrial chain bottlenecks. It uses the statistical database from 2000 to 2023 on China Economic Network, and combines input-output table and input-output extension table data for theoretical deduction and empirical testing. This study constructs the "bottleneck" industrial chain centrality (KICce) and industrial chain intermediary degree (KICme) index as the dependent variables to measure the degree of independence and controllability over key links in the industrial chain.
The study comes up with five conclusions. Firstly,two-way FDI effectively increases the independence and controllability over the key links that are bottlenecks in industrial chain,and its enhancement effect on the centrality of the industrial chain is stronger than that of the intermediary degree of the industrial chain. Secondly,two-way FDI to increase the independence and controllability of the key links in industry chain as a percentile incremental function,the intensity of the two-way technology spillovers,OFDI reverse technology spillovers and FDI technology spillover effects,decrease in descending order. Thirdly,technological innovation, as a mediating variable,assumes the role of a single mediator of multiple explanatory variables between two-way FDI and the degree of independence and controllability of the key links that are bottlenecks in the industrial chain. Fourthly, two-way FDI enhances the degree of independence and controllability of key links that are bottlenecks in the industrial chain, resulting in internal "double threshold" and external "single threshold" effects. Fifthly,there is regional,industrial and time heterogeneity of two-way FDI to increase the independence and controllability over the key links that are bottlenecks in the industrial chain.
On the basis of the empirical findings,some policy implications are obtained. Firstly,the government should make targeted measures based on specific conditions to bolster the support for two-way direct investment. Secondly,the values of high-tech talents should be stressed to enhance the national capability of original innovation and basic research. Thirdly,it is essential to give full play to the advantages of the new system of pooling national resources and strengths to achieve the organic unity of the roles of the market and the government to break through the technological bottlenecks in the key links. Fourthly,more efforts will be made to foster new quality productive forces to achieve industrial innovation and industrial chain upgradation. Therefore, China should leverage its latecomer advantage in two-way FDI, as well as the benefits of technological spillover to further increase the independence and controllability over the key links that are bottlenecks in the industrial chain.