Abstract: Land resources are the material basis for human survival and development, but the extensive land management mode brings a series of serious challenges: land resources are limited, non-point source pollution aggravated, the quality of agricultural land deteriorated, agricultural carbon emissions increased sharply, agricultural land conversion, etc. This development model at the expense of resources and environment has seriously restricted the sustainable development of agricultural economy. It is of great theoretical and practical significance to scientifically analyze the spatial-temporal differences and impact mechanism of agricultural land ecological efficiency for realizing the coordinated development of agricultural land use, resources and environment, and formulating sustainable agricultural development policies. In this paper, Jiangxi Province was taken as a typical case study area. First, inventory analysis and carbon emission coefficient method were used to calculate the pollution and carbon emissions of agricultural surface sources，and then it was incorporated into the SBM-Undesirable model of undesirable output. Secondly, the ecological efficiency of agricultural land was quantitatively measured and the spatial-temporal pattern of the study area was revealed in Jiangxi Province and its districts and cities from 1990 to 2017. Finally, it used the Tobit regression model to discuss the influence mechanism of relevant factors. The results showed that: (1) From 1990 to 2016, the ecological efficiency of agricultural land in Jiangxi Province showed a “first decreased and then increased” trend, with an average value of 0.749, showing an overall upward trend;(2) The spatial pattern of eco-efficiency of agricultural land in Jiangxi Province was characterized by a flat “V” feature that decreased first and then increased. The high efficiency regions changed from “serial” distribution to “spot” distribution and then to “serial” distribution, and the spatial pattern tended to be unbalanced; (3) The per capita disposable income of rural residents, multiple cropping index, cultural proportion of rural labor force above senior high school and per capita sowing area had significant positive effects on the ecological efficiency of agricultural land in Jiangxi Province, while the income gap between urban and rural areas had significant negative effects. Finally, the paper putting forward some suggestions to improve the ecological efficiency of agricultural land from the aspects of optimizing the allocation of resources, strengthening the innovation and application of agricultural science and technology, perfecting the rural land circulation system, abandoning the extensive development model of excessive dependence on resources and factors input and environmental pollution, taking the “intensive cultivation” and sustainable development of agricultural ecological civilization. Meanwhile, there are still some somewhat limitations in this study: (1) In the aspect of unexpected output, the loss of agricultural land ecological efficiency caused by unexpected output, such as rural domestic sewage or rural industrial wastewater discharge pollution, has not been considered; （2) The differences of initial land quality and soil fertility among different regions have not been included in the evaluation system of agricultural land ecological efficiency; （3) In the analysis of impact mechanism, the micro-factors such as farmers’ willingness to adopt agricultural science and technology, pollution prevention and control are not included in the analysis. The spatial and temporal differences of agricultural land ecological efficiency and its influencing mechanism are the result of many factors, which provide an important direction for further research in the future.