show Abstracthide AbstractTo elucidate the complex physiological process of the growth, development and immunity response of Sika Deer, this study evaluated the changes of miRNA profiles in the four developmental stages (juvenile, adolescence, adult and aged) of ten tissue (adrenal, antler, brain, heart, kidney, lung, liver, skeletal muscle, spleen and testes). The results showed that a total of 306 known miRNAs and 143 novel miRNAs were obtained. Many miRNAs displayed organ-specificity and age-specificity. The largest number of miRNAs were enriched in the brain, some of which were shared only between the brain and adrenal. These miRNAs were involved in maintaining specific functions within the brain and adrenal. Additionally, the adolescence-adult transition of Sika Deer was a crucial stage in its life cycle. In conclusion, our study provided abundant data support for the current research Sika Deer. It also contributes to understand the role of miRNAs play in regulating the growth, development and immunity response of Sika Deer. Overall design: The miRNA expression profiles in the four developmental stages of ten tissue in Sika Deer were generated by Illumina HiSeq2500 sequencing