Endogenous growth theory holds that technological innovation represented by patent is the source of economic growth. How to evaluate the actual contribution level of Chinese agricultural patents to economy under the condition of technology spillover remains to be further explored. Based on the planting industry data of 31 provincial administrative regions from 1985 to 2017， it analyzed the contribution of valid invention patents to economic output and their spatial composition from the perspectives of two technology diffusion ways， i.e. geography and supply-demand connection. The results show that under different spatial matrices， the significant contribution of patented technology to agricultural output is second only to chemical fertilizer and labor； under inverse distance matrix， patents generate positive spatial spillover effect due to interregional knowledge flow； under geographical adjacency matrix， technology similarity matrix and industry similarity matrix， the spatial spillover effects of patents are significantly negative， but still smaller than their positive direct effects. The different directions of patent spillover effects indicate that patents have not only a positive effect on agricultural economy decreasing with distance due to technology diffusion， but also a restraining effect caused by the property rights exclusivity in the same agricultural regionalization. Therefore， in the development of regional agricultural science and technology innovation， the economic effects of local and surrounding area patent output should be appropriately coordinated and utilized to achieve sustainable agricultural growth.