构建粮食市场有效性分析框架，基于事件研究法基本思想，采用2008年11月～2020年8月相关数据，借助VAR、BEKK等模型分析收储制度市场化改革前后玉米市场有效性及变化。研究发现，市场化收购政策实施后，我国玉米期现货市场、产业链上下游、国内外市场的价格信息传递更加通畅，玉米市场有效性提升，政策改革目标已初步实现。为巩固市场化收购政策效果，防范国际市场因素造成国内市场异常波动，应当以增强粮食安全保障能力为导向，提升我国期货市场影响力，并完善配套措施、细化补贴标准，降低市场化收购对粮食产业的冲击。

Based on the basic idea of the event study method, this paper constructed a framework for analyzing effectiveness of grain market. According to the relevant data from November 2008 to August 2020, VAR and BEKK models were used to analyze the effectiveness and changes of corn market before and after the market-oriented reform of the purchase and storage system. The study found that after the implementation of the market-oriented acquisition policy, the transmission of price information in China's corn spot market, upstream and downstream of the industrial chain and domestic and foreign markets has been more unobstructed, the effectiveness of the corn market has been improved, and the goal of policy reform has been preliminarily achieved. To consolidate the effect of market-oriented acquisition policy and prevent abnormal fluctuations in the domestic market caused by international market factors, it should be oriented to enhance the ability to ensure food security, enhance the influence of China's future market, improve supporting measures, detail the subsidy standard, and reduce the impact of market-based purchase on the grain industry.

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国家社科基金重大项目“耕地-技术-政策融合视角的‘两藏’战略研究”(21ZDA056)、中国农业科学院科技创新工程项目(ASTIPIAED-2020-01)、国家社科基金青年项目“中美贸易摩擦对中国大豆进口稳定性的影响机理与政策保障研究”(22CJY018)、河南省软科学研究计划“新发展格局下河南省粮食产业安全问题研究”(222400410185)