Based on the analysis of current status of land use in China and the research findings on land retirement from abroad,the authors suggested that land retirement could be an alternative practice for future cultivated land protection in China.Land retirement as a part of sustainable land use,can improve the quality of cultivated land and regional ecological environment,and ensure national long-term food production capacity and food security.Considering the requirement of national food security,a feasible size of land retirement was estimated.An index system consisting of natural environmental quality,utilization intensity of cultivated land and socio-economic development,was constructed to evaluate the regional suitability of land retirement for identify suitable sites for land retirement.Virtual research on land retirement of Tongzhou City of Jiangsu Province was carried out under different development scenarios.The results show that the practicable size of land retirement in Tongzhou City ranged from 661hm2 to 6 410hm2 under different development scenarios. The land retirement areas were mainly distributed in Shigang Town,Qi′an Town and Chuanjiang Town,etc.The virtual research provides a useful reference for the future land retirement policy making in China.