[Objective] On the basis of calculating the decoupling elasticity of agricultural chemical input and agricultural economy, the influencing factors of agricultural chemical input and its spatio-temporal pattern evolution were further analyzed to provide bases for the protection of agricultural resources and environment in He'nan Province.[Methods] Based on the Tapio decoupling model, the decoupling relationship between agricultural chemical input and agricultural economy in He'nan Province was analyzed. LMDI decomposition model was used to decompose the influencing factors of agricultural chemical input, and K-means method was used to cluster the agricultural chemical efficiency in He'nan Province.[Results] From 1993 to 2016, the input of agricultural chemistry in He'nan rose firstly and declined lately. The inputs of agricultural film, pesticide and fertilizer showed their respective downward trends in 2012, 2014 and 2016. In the past 23 years, the trend of the relationship between agricultural chemical input and agricultural economic growth had changed from relative decoupling and expansive negative decoupling to relative decoupling, and then to a trend of absolute decoupling in He'nan Province. The cultivated land effect was the main driving force for the increase of agricultural chemical input, and the efficiency effect had a significant inhibitory effect on agricultural chemical input, and the scale effect was not obvious. From the perspective of spatial pattern, the growth of agricultural economy in the southeastern of He'nan was highly dependent on the agricultural chemical input, and the degree of agricultural chemistry participating in agricultural economic growth in the center and the northwest of He'nan Province was relatively low.[Conclusion] On the whole, agricultural chemical input and economic development of He'nan Province showed a decoupling state, but there were still large spatial differences within the region. Differential agricultural chemical control policies should be adopted in the future.