Nitrogen (N) is an important element required for plant growth and development， which also affects plant yield and quality. Autophagy， a conserved pathway in eukaryotes， degrades and recycles cellular components， thus playing an important role in N remobilization. However， only a few autophagy genes related to N remobilization in rice (Oryza sativa) have been reported. Here， we identified a core autophagy gene in rice， OsATG8b， with increased expression levels under N starvation conditions. It was investigated the function of OsATG8b by generating three independent homozygous 35S-OsATG8b transgenic Arabidopsis thaliana lines. The overexpression of OsATG8b significantly enhanced autophagic flux in the transgenic Arabidopsis plants. It was also showed that over-expressing OsATG8b promoted growth and development of Arabidopsis， in which the rosette leaves were larger than those of the wild type (WT)， and the yield increased significantly by 25.25%. In addition， the transgenic lines accumulated more N in seeds than in the rosette leaves. Further examination revealed that overexpression of OsATG8b could effectively alleviate the growth inhibition of transgenic Arabidopsis under nitrogen (N) stress. N partitioning studies revealed that nitrogen-harvest index (NHI) and nitrogen use efficiency (NUE) were significantly increased in the transgenic Arabidopsis， as well as the 15N-tracer experiments revealing that the remobilization of N to seeds in the OsATG8b-overexpressing transgenic Arabidopsis was high and more than WT. Based on our findings， we consider OsATG8b to be a great candidate gene to increase NUE and yield， especially under suboptimal field conditions.