After the global outbreak of the COVID-19 (hereinafter referred to as the "epidemic"), some major food producing countries have restricted exports, and some countries have added barriers to international trade and blocked logistics, leading to the distortion of healthy global food supply and demand relations, and the global food price has soared, causing governments and people of all countries to pay close attention to food security. The traditional factors that affect food security include changes in actual production, stock, consumption, and trade volume, which trigger changes in supply and demand relationships and affect prices. In the context of highly developed internet, the above factors, after being disseminated and fermented through the internet, will form a certain scale of social public opinion, and its dissemination effect may even distort short-term supply and demand relationships and prices, which is also an important factor affecting food security. This article takes several international and domestic food related public opinion events during the epidemic as examples to analyze the impact of public opinion on food security under the Internet ecosystem. It proposes that the foundation of food security still needs to be continuously strengthened, and that the relationship between normal and extreme thinking security, micro security and macro security, the relationship between current security and future security, and the continuous improvement of information dissemination and public opinion management under the Internet should be addressed, To provide reference for grasping the positive guidance expectations and managing the initiative of public opinion.