Abstract: In order to ensure national food security, grains production is highly concerned by the Chinese government, however the ecological environment of the agricultural system has been greatly neglected. As a result, the problem of pesticide overapplication in grain production is quite serious. Therefore, aiming at reduce the application of pesticide and improve its use efficiency according to local conditions, it is of great significance to focus on the degree of pesticide overapplication in the production of the three major grains of rice, wheat and corn in China, and to clarify their spatio-temporal evolution characteristics and influence factors in different regions. Based on provincial panel data of pesticide application in the production of the three major grains from 2000 to 2022, by using the damage control function model, GIS spatial analysis, and the panel economic model, this paper quantitatively measures the degree of pesticide overapplication, reveals the spatio-temporal evolution characteristics, and discovers the influence of various factors respectively, in the three major grains production. The results show that:(1) From 2000 to 2022, there is an obvious fluctuant increase in the three indictors of the actual application, optimal application and overapplication degree of pesticide in the production of the three major grains, and the average value of the three indicators shows the characteristics of rice > wheat > corn. From the perspective of regional differences, pesticide overapplication levels of the three major grains are similar in the eastern and central regions, so are in the western and northeastern regions. However, the overapplication levels in the former two regions are significantly higher than that in the latter two regions. (2) From the perspective of provincial spatio-temporal evolution, the overall level of pesticide overapplication in rice production areas shifts from the spectrum of slight excess to moderate excess from 2000 to 2022, while that of wheat and maize production areas changes from the spectrum of not excess to moderate excess. Moreover, the moderate excess and severe excess areas in rice production are highly concentrated in the eastern and central regions. (3) The six factors, urbanization rate, average grain production scale per household, education level of farmers, fiscal expenditure on agriculture, cultivated land transfer areas, and the policy of zero growth in pesticide application, have varying significant inhibiting effects on pesticide overapplication in the three major grains production. Conversely, the five factors, temperature, natural disasters, GDP per capita, grain prices, and per capita disposable income of rural residents, have varying significant promoting effects. The results of this paper can clarify the space size of the work to reduce the application of pesticide and improve its use efficiency in the three major grains production in different regions of China, and provide a decision-making basis for local governments to carry out that work.