Due to the in-depth analysis of the next generation sequencing data，many small noncoding RNA with different functions have been revealed. In recent years，transfer-RNA derived small RNAs（tsRNAs） have attracted wide attention. There are two main types：tRNA-derived stress-induced RNA（tiRNA） and tRNA-derived fragment（tRF），which are produced according to their positions in precursor or mature tRNA transcripts. These tRF & tiRNA molecules are heterogeneous in size，the nucleotide composition，biogenesis，and function. New research shows that tRF & tiRNA molecule is not only fragments of tRNA degradation，but also plays a regulatory role in specific physiological and pathological processes. In this paper，the types of tRF & tiRNA are reviewed，and the new concepts of biological functions and mechanisms of tRF & tiRNA molecule are proposed. The potential applications of tRF & tiRNA in human diseases are emphatically introduced，and existing issues and future research directions have been proposed.