Abstract: Returning straw to farmland is inherently limited and difficult. Encouraging farmers to sell straw through policy regulation and normative cognition is therefore critically important for enhancing the high-value, off-field utilization of straw and for achieving high-quality agricultural development. This study aims to examine the factors that influence farmers’ decisions to sell straw, focusing on the roles of policy regulation and normative cognition. We develop an analytical framework for farmers' straw-selling decisions and apply it to survey data from 715 farm households in Huanggang City, Hubei Province. Using the Heckman two-stage model and the IV-Heckman model, we analyze the effects of policy regulation, normative cognition, and their interaction on farmers' straw-selling decisions. We also investigate the heterogeneity of these decisions and their determinants across different groups of farmers. Our results indicate that, after testing for endogeneity and conducting robustness checks, both policy regulation and normative cognition are significant drivers of farmers'  decisions to sell straw. Furthermore, in the initial participation decision stage, policy regulation and normative cognition exhibit an interactive effect on these decisions, demonstrating a complementary relationship between the two. This interaction, however, does not extend to the subsequent stage of selling intensity. Additionally, significant group heterogeneity is observed: the impact of policy regulation and normative cognition on straw-selling decisions varies markedly among farmers with different locational characteristics and farm sizes. Consequently, policy implementation should fully leverage the flexible constraints and guiding role of normative cognition to foster synergistic effects with policy regulation. Differentiated policies tailored to local conditions should then be implemented.