miRNA is widely involved in the development of plants. The leaf type varied among different Chinese kale varieties. To understand evolutionary characteristics of the miR156a family and its expression pattern during leaf development of Chinese kale, we performed bioinformatics analysis on different miR156a members and the corresponding precursor premiR156a genes in Chinese kale. Morphology of leaves of four Chinese kale varieties were recorded, and expression of miR156a precursors were analyzed by qRTPCR in different tissues of ‘Cuibao’. In addition, the expression levels of premiR156a and SPL2/10/15 in the first true leaves, mature leaves and ‘Gu’ leaves were also measured in ‘Cuibao’ and ‘Gailiangxianggu’. The results contained four aspects as below. (1) Multiple sequence alignment and evolutionary tree analysis showed that miR156a family and premiR156a3p_1 was highly conserved in Chinese kale during evolution. Secondary structure prediction revealed that each member of premiR156a could form a stemloop structure and contained two or three miR156a’s sequences. Target gene prediction showed that miR156a5p and miR156a mainly targeted SPL family while miR156a3p_1 targeted different genes such as CTPS. (2) The leaf shape of ‘Cuibao’ and ‘Gailiangxianggu’ are the most similar and the difference is that ‘Gailiangxianggu’ has its unique ‘Gu’ leaves. The qRTPCR analysis exhibited that the expression level of premiR156a was high in the leaves of ‘Cuibao’ at vegetative growth stage. (3) The expression level of premiR156a members varied in different types of leaves in ‘Cuibao’ and ‘Gailiangxianggu’. The expression of premiR156a was abundant in mature leaves and ‘Gu’ leaves, while the expression levels of premiR156a3p_1 and premiR156a5p were higher in the first true leaves. (4) Target gene analysis showed their different expression trends existed in different varieties. In ‘Cuibao’, the expression level of SPL10/15 was high in the mature leaves while the expression level of SPL2 was reduced. In ‘Gailiangxianggu’, the expression level of SPL10 was reduced in the mature leaves and ‘Gu’ leaves while SPL15 was high in the ‘Gu’ leaves and no difference was detected in the transcript amounts of SPL2. As a result, members of miR156a and their target genes SPL2/10/15 may be involved in regulating leaf development of Chinese kale. The target genes of miR156a in different varieties may be different, which might related to the various leaf phenotypes in Chinese kale.