Abstract: In order to explore the mechanism of marginal cleavage in Betula pendula 'Dalecarlica', the research took Betula pendula 'Dalecarlica' and Betula pendula as research projects, based on leaf morphological characters and anatomical feature, we conducted qRT-PCR of leaf cleavage relating genes in apical buds, leaf tips, lobes, sinuses and other tissues, and also measured the endogenous IAA content and analyzed the GUS dyeing of IAA living tag(DR5). It turned out that Betula pendula 'Dalecarlica' blades owned three or four lobes from base to tip in both leaf sides, the veins on the back showed obvious tubular uplift, leaf width, mean distance between secondary veins, cross sectional areas of main veins were respectively bigger, namely 21.12%, 12.64%, 21.46%. Tissue expression characteristic analysis of BpmiR164s and target genes demonstrated that BpmiR164-2 and BpCUC2 played an important role in the formation of lobes, which was the major regulating gene in producing lobes; tissue expression characteristic analysis of BpPINs indicated that only BpPIN2 and BpPIN5 in six auxin efflux carriergenes presented up-regulated expression; living tag of endogenous IAA manifested that IAA content enriched in apical buds and spires, meanwhile, the tissues of leaf tips, teeth and lobes in leaf expressed more IAA, we also got the IAA distribution features from results of LC-MS in above-mentioned tissues. Above all, the formation of lobes was bound up with polar transportation of hormone in the veins and some related gene regulation.