This study aimed to reveal terrestrial plant biomass allocation between aboveground and belowground tissues under nitrogen (N) deposition and to provide a foundation for studying carbon (C) and N cycles, stand harvests, direct cultivation in different ecosystems, and relevant research and practices regarding plant biomass allocation. Through synthesizing data from 63 peer-reviewed publications, we quantified the response of plant biomass allocation to N deposition by meta-analysis and assessed the influences on plant biomass allocation of different ecosystem types, plant species, and N forms and levels. This study found that N deposition significantly increased the aboveground biomass of plants, with plant leaf biomass and stem biomass showing an increasing trend under N application. However, although underground biomass increased under N deposition, the increase was less than that of the aboveground biomass. Fine root biomass and coarse root biomass did not change significantly under N deposition. The root:shoot ratio decreased significantly under N application. Leaf weight ratio, stem weight ratio, and root weight ratio did not change significantly under N deposition. In addition, subgroup analysis showed that there were differences in the response of the root:shoot ratio and total biomass to N deposition for both ecosystem type and plant species. Herbaceous plant biomass accumulation increased significantly more than that of woody plants, which meant N deposition could increase the coverage of herbaceous plants. Nitrogen forms significantly affected the response of the root:shoot ratio to N application, with ammonium nitrate having a more significant effect on the root:shoot ratio than urea. The response of aboveground biomass to N application was significantly affected by the level of N application. Aboveground biomass was promoted the most at a medium N level (60-120 kg hm^-2a^-1) and at a high N level (≥ 120 kg hm^-2a^-1), there was less of an effect, which was consistent with the change in total biomass. This result indicates that excessive N deposition inhibits plant growth. In addition, there were temporal differences in the effects of N application on the aboveground biomass of plants. In this study, when the N application time was longer than 3 years, the effect of N application on aboveground biomass was negligible. In conclusion, short term N application will allow most terrestrial plants to allocate more biomass to aboveground parts and the biomass accumulation of herbaceous plants is better than that of woody plants. These conclusions will provide a reasonable scientific basis for future correlative studies on plant carbon storage, community structure, tree species diversity, and vegetation dynamics under N deposition.