Straw returning is important for rural ecological management and sustainable agricultural development. Using farm survey data for Anhui Province, China, in 2020, we applied the double‐hurdle model to investigate the impact of agricultural machinery services and land fragmentation on farmers' straw‐returning behavior, and to explore the relationship between agricultural machinery self‐service and outsourced service. Self‐service had a significant positive effect on farmers' straw‐returning behavior, while outsourced service had a significant positive effect only on degree of adoption. Land fragmentation had a significant negative effect on farmers' straw‐returning behavior, and significantly inhibited the effect of self‐service on adoption decision. Complementarity existed between self‐service and outsourced service in farmers' straw‐returning adoption decision, and the effect was more pronounced among smaller‐scale farmers. There was significant substitutability between self‐service and outsourced service in degree of adoption among larger‐scale farmers. Transfer and integration of rural land, increasing agricultural machinery purchase subsidy, upgrading farmers' self‐service capability, and promoting development of socialized agricultural machinery services should be implemented to promote crop straw returning. EconLit Citations: Q01, Q16.