Abstract: In order to promote the further development of large-scale land management and help small farmers connect to big markets, it is essential to take into account both the supply and demand of agricultural machinery services. This study firstly analyzed the mechanism of agricultural machinery service outsourcing and supply on farmers’ land scale management in theory, then used the OLS model to empirically analyze the impact of agricultural machinery service outsourcing and agricultural machinery service supply on farmers’ land scale management. In order to ensure the reliability of the model results, the instrumental variables were introduced and the 2 SLS model was used for further analysis. Finally, the family farm machinery assets were selected as the moderator variables to establish a moderation effect model to analyze the relationship between the farm machinery service outsourcing and supply. The results showed that the scale operation had the influence of the heterogeneity of farmers. The number of agricultural machinery service outsourcing links per farmer with the operation scale between 12.62 hm~2 and 25.24 hm~2 was the highest, which was 4.08. The average number of agricultural machinery service outsourcing links of farmers with operation scale of 0-12.62 hm~2, 25.24-37.86 hm~2, and more than 37.86 hm~2 were 3.48, 2.29 and 1.45, respectively. This showed that with the expansion of the scale of farmers’ operations, the number of outsourcing links of agricultural machinery services presented an inverted “U” trend. The supply of agricultural machinery services had a positive impact on the scale of land management, with a significant coefficient of 0.549. From low to high, the number of service supply links per household was 0.1, 0.6, 1.79, and 3.6, respectively, that is, with the expansion of the scale of operation, the service supply of farmers also gradually increased. Household agricultural machinery assets could negatively adjust the impact of agricultural machinery service outsourcing on land scale management, and there was a substitution relationship between self-purchased agricultural machinery and agricultural machinery service outsourcing.