Great challenges regarding land use conflicts in rapid urbanization call for deeper research on land use efficiency (LUE) from the perspective of sustainable land use for the coordination among food security, economic development, and ecological protection. This study firstly develops a new framework of LUE based upon the expectations in land use and the coordination among three sub-categories in food production, economic development, and ecological protection, then, uses the coupling coordination degree model to quantify the spatial differentiation characteristics and coupling coordination relationships among three sub-categories, and finally uses the multivariable linear regression and geographical detectors to analyze the impact factors of sub-category efficiency. The framework is applied to Jiangsu Province in eastern China by using ten indicators (i.e., cultivated land quality, grain output, multiple cropping index, average GDP per km2, population density, proportion of industry and service industry, vegetation cover index, water conservation index, soil retention index, and carbon sequestration index) in terms of food production, economy, and ecology analysis at the county level. Compared with expectations, the LUE of Jiangsu in food production, economic development, and ecological protection is 54.15%, 85.56%, and 54.95%, respectively, indicating that Jiangsu has great potential for sustainable land use. The coupling coordination degree in land use generally synchronizes with the coupling degree, accounting for 65.34% of the province's area, of which 75.00% are in lower-coupling & lower-coordination, medium-coupling & medium-coordination. Among all the factors, proportion of industry and service industry, population density, multiple cropping index, average GDP per km2, and water conservation index have the most important roles in the coordinated development of land use sub-systems. Therefore, we suggest land use/urban management need to implement more integrated planning and differentiated strategies to stimulate land use potential and maintain efficient and sustainable land use.