Abstract:The improvement of nutrient use efficiency is the double demanding for both food and environmental safety. In the below-ground, there are large amount of various organisms including plant roots, microbes, and animals. The below-ground organisms are involved in the mobilization, transformation, uptake and transport of nutrients, being the main driver of the above-ground productivity and nutrient use efficiency. This review summarized four aspects of research progresses: (1) biologically signaling basis and nutrient transformation in soil-root-microbe interfaces; (2) microbial community composition and nutrient transformation; (3) plant roots and nutrient-efficient uptake; (4) microbes and nutrient-efficient acquisition by roots. Based on these progresses, four research focuses are suggested to be enhanced in the future: (1) the function and regional differentiation of soil organisms; (2) the relationship between soil microbe-regulated processes and nutrient efficiency; (3) the root characteristics of nutrient-efficient plant varieties; (4) the development of biological reagents for nutrient-efficient use. The technological development and mechanistic clarification will hopefully promote the uncovering of the "black box" of the below-ground organisms, ultimately contributing to the improvement of nutrient use efficiency by regulating the interactions between the above- and below-ground organisms.