Abstract: In this study the evolutionary characteristics of apple miR396 family and their expression pattern during adventitious root development were analyzed. The results demonstrated that the apple miR396 family contained 4 mature sequences and 7 precursor sequences. Mfold analysis showed that 7 precursor sequences of pre-miR396 members could form a typical stable stem loop structures，and their minimal folding free energies（ΔG）ranged from–62.9 to–51.9 kal ? mol-1. Phylogenetic tree analysis showed that the genetic relationship of pre-miR396 family in apple could be classified into 3 subgroups （G1，G2 and G3）. According to its homology，each subgroup contained 11，9，19 members respectively. Prediction of target genes for apple miR396 family revealed that their targets were MdGRF1，MdGRF2 and MdGRF5 genes. The members of miR396 family showed significantly higher expression level in lateral roots and fruits as compared to other tissues. In addition，the candidate target genes kept higher expression level in flower buds and axillary buds than other tissues. During the process of adventitious root development，the expression patterns of different miR396 family members had significant differences，and overall expression was up-regulated，however，the candidate target genes were down-regulated during the adventitious root development. Exogenous IBA treatment significantly induced the expression of miR396 family members，especially in induction and root growth phases during adventitious root formation.

Key words: apple, miR396, adventitious root development, bioinformatics analysis, gene expression