Currently, the quality and quantity of agricultural resources have entered a period of hard constraints, agricultural environmental pollution has become increasingly serious, and the quality of arable land has been declining.In order to promote the sustainable development of agriculture and explore the sustainable use of arable land, this study takes China as an example to analyse the impacts, mechanisms and regulating effects of crop fallow rotation on the ecological efficiency of arable land.Firstly,This study selected the panel data of Chinese provinces and municipalities directly under the central government from 2010 to 2020, and firstly used the non-expectation Super-SBM model to measure the ecological efficiency of arable land in each region of China;Secondly, the effects and differences in effects of crop fallow rotation on the ecological efficiency of arable land were analysed using an asymptotic differences in differences model with two-way fixed effects;Finally, the mechanism of crop fallow rotation and the external influencing factors in the implementation process were explored through regulating analysis and mechanism analysis.The regression results indicate that crop fallow rotation can significantly contribute to the ecological efficiency of arable land, and the results still hold after a series of robustness tests;Differential analyses indicate that crop rotation promotes ecological efficiency of arable land more than crop fallow;The analysis of the regulating effect shows that the small peasant economy reduces the effect of crop fallow rotation, while the government's support to agriculture and the cultivation of new agricultural management subjects can enhance the effect of crop fallow rotation;Mechanism analysis shows that crop fallow rotation can reduce the redundancy level of input factors, reduce agricultural carbon emissions and surface pollution to promote the ecological efficiency of arable land.Based on this, the study makes the following recommendations:1.Strengthen the promotion of crop fallow rotation,implemented with crop rotation as the main focus, with crop fallow as the secondary focus;2.Strengthen the cultivation of new agricultural management subjects, and promote the moderate-scale operation of agriculture;3.Improve the efficiency of the use of arable land, and actively promote agricultural carbon emissions reduction and the treatment of surface source pollution.