Agricultural socialized service as an inevitable product of agricultural division and a mediator of elementeffective allocation, plays a oritical role in agricullural modemization. This paper, based on 134 cases of “entiremechanization + comprehensive agricultural affairs” nationwide, combined with in-situ investigation data ofcomprehensive agricultural affairs in H city’s L district, J city’s W district, Zhejiang province, uses rooting theory andNVivo12 soliware for data coding and analysis, and constructs an agricultural socialized service system model to studythe mechanism, dynamics and challenges of its promotion on industrial upgrade. Agricultural socialized service systemis composed of two key categories, production supporting service and factor intensive service, covering 10 majorcategories and 35 categories. Production supporting service boosts marginal benefits from increasing productionefficiency, decreasing costs and optimizing resources allocation; while factor intensive service uses professionalinterediate imputs to promote human capital development and innovation through technical advances, dligitalization andbrand markelting. Agricultural socialized service further optimizes process connection and henefits connection so as toraise overall agricultrral competitiveness and marginal benefits of industrial chain. Five drives including marketleading, enterprise consolidation, technical supports, policy supports and local connection jointly promote agriculturalsocialized service and industrial upgrade; however, agricultural socialized service faces such difficulties as lowindustrial added values and shortage of agricultural talents. This paper presents suggestions on promoting polioystandardization, accelerating agricultural technical conversion and cultivating agricultural talents for high qualityagricultural socialized service.