Biological nitrogen fixation (BNF) in forest ecosystems plays a very important role in global nitrogen (N) cycling, because forest ecosystems cover 30% of the global land area and represent nearly half of the N fixation that occurs in terrestrial ecosystems. Additionally, these ecosystems harbor abundant N-fixation microbes, including both symbiotic and free-living N-fixation bacteria. It is generally believed that environmental conditions (e.g. temperature, moisture, and light intensity) and nutrient availability are the most important factors regulating BNF in ecosystems. Among these factors, the effects of nutrient availability have recently received increasing attention. In the last several decades, anthropogenic activities have greatly modified the global biogeochemical cycles of N and other mineral nutrients. For example, the quantity of global N deposition increased from 41 Tg N /a in 1950 to 103 Tg N /a in 2000. Long-term N deposition may exert direct effects on forest BNF by reducing the competitive advantage of free-living N-fixation bacteria or by reducing the energy allocated to symbiotic N-fixation bacteria. N deposition may also lead to imbalances in mineral nutrient proportions that play vital roles in the growth of N-fixation bacteria. Phosphorus (P), for example, is thought to be a major component of microbial cell membranes and also to be directly related to the formation of adenosine triphosphate (ATP), which is very important for nitrogenase function. In addition, many rock-derived nutrients (e.g. Ca, K, Mo, and Fe) are depleted and their availability becomes poor during forest succession. Deficiency of these mineral nutrients may consequently influence forest BNF by limiting the growth of N-fixation bacteria. In recent decades, mineral nutrient addition experiments (in the lab or in situ) have been widely used in Europe and North America to investigate how nutrient availability influences forest BNF. However, little information on how forest BNF responds to nutrient addition is available from China, although N deposition is projected to increase with the rapid growth of the Chinese economy in the future. In this paper, we review the impacts and underlying mechanisms of mineral nutrient addition on forest BNF, based on the available literature. The objectives were to enhance our understanding of how mineral nutrient addition regulates forest BNF and to provide scientific data for sustainable forest management. This review focuses on the following four aspects: (1) The concept of forest BNF and the principal measuring methods; (2) The effects of mineral nutrient addition on forest BNF, including the N fixation by free-living organisms occurring in the upper soil, the lichens and mosses growing on the litter layer, and symbiotic N fixation via relationships with root nodule plants (e.g., legumes). In general, N addition decreases forest BNF, whereas addition of P or other nutrients has a positive impact. In addition, the combined addition of N and P, or P and other mineral nutrients, increases forest BNF; (3) The mechanisms underlying forest BNF can be divided into biotic (e.g., variance in the abundance or richness of N-fixing bacteria, the cover or richness of epiphytes, and the biomass of root nodule plants) and abiotic mechanisms (e.g., soil acidification and changes in the available carbon content); (4) The limitations of the current research and our suggestions for further research on forest BNF.