Abstract: Abstract: According to the ecological characteristics of subtropical hilly region, "planting system-beef cattle-organic fertilizer-cropping system" circular agriculture model was constructed which including planting system, breeding system,waste harmless treatment system and product marketing service system. In order to reveal the characteristics of nitrogen and phosphorus flows in each subsystem of circular agriculture model，the Input-Output model of nitrogen and phosphorus was constructed that based on the input-output model theory, and determined the calculation method of model parameters. Take Jinjing town of Changsha county as an example, the results show that the established nitrogen and phosphorus Input-Output model can reflect the nitrogen and phosphorus flow of intermediate and final products in each subsystem of circular agriculture model and establish the balance of nitrogen and phosphorus between the production and distribution in main products of circular agriculture system. Theresearch findings can not only provide scientific reference for efficient utilization of nitrogen and phosphorus resources of agriculture and animal husbandry compound circular agriculture model but also provide theoretical basis for the study on the mechanism of nitrogen and phosphorus cycling in agriculture and animal husbandry ecological system.