Taking customer firm standardization in agricultural supply chains as the entry point， this study empirically tests the impact and mechanism of customer enterprise standardization on the information environment of upstream and downstream enterprises in the agricultural supply chain，using quarterly consolidated data of agricultural listed companies from 2008 to 2022.The study reveals that the implementation of standardization construction by customer enterprises in the agricultural supply chain can produce a positive spillover effect of information，which helps to mitigate the “bullwhip effect”.The results of mechanism analysis show that the standardization of customer enterprises in the agricultural supply chain enhances information transparency among upstream and downstream enterprises，reduces information verification costs，and promotes “supply chain coordination”.These improvements alleviate information asymmetry within the supply chain and，in turn，reduce the bullwhip effect.Heterogeneity analysis shows that the mitigating effect of customer firm standardization on the bullwhip effect is more pronounced when supplier firms are larger in scale，stronger in technological capability，geographically less proximate，located in regions with weaker contractual environments，and situated in supply chains with lower degrees of industrial extension.This study provides a fresh perspective for addressing issues such as optimizing the agricultural supply structures，alleviating overcapacity and improving efficiency.