The development of agricultural machinery socialized services is an important pathway for promoting the organic integration of small-scale farming with modern agriculture, strengthening the national food security system, and adjusting the planting structures. Based on data from the CLDS in 2014 and 2016, this study constructs an unbalanced panel dataset and employs a difference-in-differences （DID） model to empirically analyze the impact and mechanism of agricultural machinery socialized services on agricultural planting structures. The study finds that agricultural machinery socialized services significantly promote grain production, leading to “grain-oriented” trend in planting structures. The conclusion remains robust after addressing sample selection bias, changing sample sizes, replacing models, and conducting placebo tests. The mechanism test shows that land transfer and the migration of non-agricultural labor act as moderators between agricultural machinery socialized services and the “grainoriented” planting structure, reinforcing the positive impact of machinery socialized services on the shift towards grain production. Further analysis reveals that the impact of agricultural machinery socialized services on planting structure varies by age and region, significantly promoting the grain plating decisions of farmers under 60 and those in central and western regions. Based on this, this paper proposes to improve the agricultural socialization service system, improve the outsourcing service market function, improve the land transfer trading platform, promote the large-scale land transfer, adapt to local conditions, implement differentiated agricultural socialization service development strategies and suggestions, promote agricultural scale management, and provide guarantee for ensuring food security.

发展农机社会化服务是促进小农与现代农业有机衔接，强化国家粮食安全保障能力的重要路径，也是推动种植结构调整的重要因素。基于2014年和2016年CLDS两期数据构造非平衡面板数据，运用双重差分模型实证分析农机社会化服务对农业种植结构的影响及作用机制。研究表明，农机社会化服务显著促进粮食生产，使种植结构呈现“趋粮化”特征，在解决样本自选择性偏误、改变样本容量、更换模型和安慰剂检验等稳健性检验后，结论依然成立。机制检验表明，土地转入和非农劳动力转移在农机社会化服务与种植结构“趋粮化”之间存在调节作用，强化农机社会化服务对种植结构“趋粮化”的促进作用。进一步分析发现，农机社会化服务对种植结构的影响具有年龄与地区异质性，显著促进60岁以下和中、西部地区的农户粮食种植决策。据此，提出完善农业社会化服务体系，健全外包服务市场功能；健全土地流转交易平台，推动土地规模化流转；因地制宜，实行差异化的农业社会化服务发展策略等建议，促进农业规模经营，为确保粮食安全提供保障。