Based on the classical theory of division of labor,this paper explores the relevance between self-sufficiency service and subconstracting service,including complete substitution,invariable substitution elasticity and complete complementarity,and further discusses its influence on the vertical division of labor in agriculture.The analytical results indicate that:(1) If the relevance between self-service and subconstracting service is completely substitutable or partially substitutable,the improvement of the transaction efficiency and management efficiency of the subconstracting service and the improvement of the subconstracting service’s professional economic level will promote the vertical division of labor in agriculture; (2) If the relevance between self-sufficiency service and subconstracting service is completely complementary,the vertical division of labor in agriculture depends on which side is weaker,the self-sufficiency service or the subconstracting service.When the subconstracting service is at a disadvantage,improving its transaction efficiency,management efficiency and professional economic level of will deepen the vertical division of labor in agriculture.Conversely,improving the transaction efficiency of subconstracting service market will induce the endogenous division of labor and the vertical integration of agricultural production.Besides,the development of the non-agricultural employment market and the product market will induce farmers to reduce and even abandon self-sufficiency service,which is beneficial to the development of the vertical division of labor in agriculture in the long run.Finally,the findings imply that exploring the relevance between agricultural intermediary services provides a new possibility for deepening the theory of division of labor and also provides a theoretical reference for formulating the policy of developing socialized agriculture and defining the law of agricultural division of labor.