Digital technology, with its wide accessibility, real-time interactivity and efficient information dissemination capabilities, has opened up a brand-new path for the popularization and transmission of disaster risk knowledge. The digital promotion of disaster prevention knowledge obtained, exchanged and internalized through the Internet has been deeply integrated into the traditional knowledge promotion system dominated by the government, shaping the behavioral logic of farmers in disaster preparedness. Using the Logit model and 685 household questionnaires from flood-threatened areas in Sichuan Province, China, this study explored the effects of digital and traditional disaster prevention knowledge promotion methods on farmers' disaster preparedness behavior. It is found that: (1) Traditional knowledge promotion can significantly improve farmers' disaster preparedness behavior, and digital knowledge promotion can also significantly improve farmers' disaster preparedness behavior. The conclusions are still valid after considering sample self-selection and robustness test. (2) Both the traditional and the digital promotion strategies can significantly improve catastrophe avoidance behavior when they are utilized concurrently, with digital strategies exhibiting a stronger marginal effect. (3) The two extension methods have a substitution effect on farmers' disaster preparedness behavior, indicating that farmers' reliance on one type of promotion method will weaken the behavioral promoting effect of the other type. Therefore, to further strengthen the effectiveness of disaster prevention and management, this paper proposes to optimize traditional disaster prevention publicity strategies, advocate farmers to adopt digital learning approaches, and build an interactive online and offline disaster prevention knowledge dissemination system.